Field of the invention

The invention relates to a novel porous material comprising porous particles coated with a cross-linked polybenzoxazine having free phenol groups, wherein the polybenzoxazine is a polymer product of a monomer selected from the group consisting of formula I, formula II, and formula III. The invention further relates to a composition comprising said porous material, to a printable or coatable ink and a component, such as an electrode, comprising a conductor coated with the composition comprising said porous material, wherein the component may be an electrochemical cell, such as an energy storage device, a battery, a super capacitor, a sensor, a printed electrochromic cell, or a transistor or combinations thereof. The invention also relates to methods for producing said porous material and said composition and use of said composition or said component in a sensor or in an energy storage device.

Background of the invention

Electrochemical cells used as e.g. batteries, capacitors and sensors are present everywhere in the society today. Electrodes for electrochemical cells based on organic materials have attracted much attention because of their generally more environmental sustainability and tunable properties. However, there are several drawbacks with existing organic electrode materials since they typically do not meet the requirements relating to lifetime and stable performances and low manufacturing costs. Further, the starting materials are often very expensive and the components difficult to produce. Thus, there is a need for improved, more robust, cheaper and more easily attainable materials with stability in order to manufacture electrochemical sensors, energy storage and organic electrochemical components, with more stable performance and increased lifetimes and at the same time with easier, cheaper and more sustainable methods. Summary of the invention

The need for immobilization of redox molecules within the field of organic electrodes, e.g. in biosensors and energy storage devices, is one of the main challenges for organic electrodes. Chemically, the problem is that coupling reactions forming covalent bonds are needed to anchor redox molecules to a substrate, or to link monomeric redox monomers into a cross- linked and insoluble network. Normally, the redox functional group of the molecules are often reactive centers of the molecule itself. This complicates the coupling reactions used to immobilize the molecules as the polymerization or cross-linking coupling reactions may affect the redox groups. The reactive groups involved in the coupling reactions can react with the redox group, or the redox group can disturb the coupling reaction. In this way, redox activity and yield of the coupling reactions can be compromised.

In the prior art, so called protective group strategies, where for example the redox group of a polymerizable redox molecule is protected during polymerization are employed. Such strategies have for example been applied in the field of organic radical batteries (ORB). The development of ORB started with the realization that electrodes containing stable radicals showed redox properties. It was found that the electrodes discharged by migration of the radical molecules. As a remedy, polymeric forms of organic radicals were developed. However, this is not enough to prevent migration of the radical molecules, as there is a need to cross-link the polymers as well as to limit migration. Therefore, these advanced protective group strategies for the synthesis of immobilized redox molecules are complicated and costly, and the environmental benefits of using organic materials may be lost in these processes.

Further, in the field of biosensors the problem is how to combine a stably immobilized redox function in an electrode material for e.g. the detection of peroxide and oxygen. Today, polyhydroquinone-reduced graphene oxide (PHQ-rGO) have been developed to function in electrodes with immobilized redox functions in biosensors. However, these suffer from several drawbacks, for example that graphene oxide (GO) is very expensive. Further, PHQ is a linear, i.e. unbranched, soluble polymer, whereas cross- linked and insoluble networks are needed for the immobilization of the redox molecules. Although, it would be possible to cross-link PHQ via the hydroquinone groups this would reduce the number of functional redox groups in the material that are available for redox reaction. Crosslinking of PHQ would likely involve phenol groups making these phenol groups inaccessable for redox reactions.

Another desired application is redox inks for use in electric capacitor devices, energy storage devices or sensor components, which are currently not on the market because of the lack of processable redox polymer compositions. Further, the redox polymers known in the art are expensive and difficult to manufacture. In addition the redox polymers require mixing with a conductor, wherein the mixing has to be on the molecular level for contact between redox function and conductor the be established. For charge transport between redox groups and conductor the distance between redox groups and conductor should be in the range of, preferably smaller than the tunneling distance, 1-2 nm. Accordingly, nanostructured materials are commonly expensive and may be unstable and hazardous.

The key objective of the invention is to provide a redox electrode material in the form of porous conducting particles coated or loaded with an immobilized and cross-linked redox polymer, and where the loaded redox polymer is loaded so that the particles retain the porosity and is located close enough to the conducting particle so that charge can be transported between the conducting particle and the redox polymer. Further, the retained porosity, which is one of the key features of the present application, enables ion transport between the redox polymer and the bulk electrolyte. In other words by coating the porous particles it means that the particles are loaded with immobilized and cross-linked redox polymer. The coating or loading may be applied in the form of a layer on the porous particles or may be comprised within the pores of the material, so that particles with a retained porosity are obtained. In view of the above, it is an object of the present invention to provide an improved porous material, i.e. a porous material with a novel functionality, an improved composition, i.e. a composition with improved properties, e.g. wherein the composition may have tailored redox properties, or a new function, an improved printable or coatable ink, an improved component and improved production methods which altogether alleviate the above-mentioned drawbacks. One example of an improved property of the porous material relates to the porosity of the material which enables ion transport in a structure where ion- and electron conduction pathways are interpenetrating.

Another object is to provide such a composition, comprising the porous material of the invention, designed for a printable or coatable ink which mitigates solubility problems associated with redox inks and consequently enables printing and/or coating of the ink.

Another object is to provide such a composition, comprising the porous material of the invention, designed for producing components, such as electrode components, wherein the porous material may be an electrically conducting carbon material coated or loaded with the polybenzoxazines (PBz) according to the present invention for use in electrochemical cells, such as energy storage devices, batteries, super capacitors, sensors, printed electrochromic cells or transistors.

Another object is to provide such a composition, comprising the porous material of the invention, designed for producing components, such as electrode components, wherein the porous material may be an electrically conducting carbon material provided with the polybenzoxazines (PBz) according to the present invention for use in electrochemical cells, such as energy storage devices, batteries, super capacitors, sensors, printed electrochromic cells or transistors, With the term “provide with” means that the polybenzoxazines may be coated or loaded on to the surface and/or in the pores of the porous material. It also means that the electrically conducting carbon material after coating or loading of the polybenzoxazines still has to be porous such that ion transport within the material is possible. The coated or loaded material has to be porous in order to be able to achieve an electrochemical effect during operation. With coating means that the surface and/or the pores of the material are covered. The coating or loading may be partially covering, semicovering or fully covering the porous material without fully filling the pores of the material. The loading or added coating layer to the porous material may be seen as the amount of added monomer per weight of porous material.

Another object is to provide such a composition, comprising the porous material of the invention, designed for use in a biosensor, wherein the porous material is mesoporous silica coated with the polybenzoxazines according to the present invention.

Another object is to provide such a method for producing a porous material by coating porous particles with a cross-linked hydroquinone-based polybenzoxazine and that the cross-linked hydroquinone-based polybenzoxazine may be provided as a thin layer, wherein the layer may be partially covering, semicovering or fully covering the porous material without fully filling the pores of the material, at a minimum specific surface area of the porous particles and thus the spreading of the benzoxazine enables formation of a coating onto the surface of the porous material without blocking of the pores.

Another object is to provide such a method for producing a porous material by loading conducting and porous particles with a cross-linked redox polymer, a hydroquinone-based polybenzoxazine and that the cross-linked hydroquinone-based polybenzoxazine is located in close vicinity to the conducting material. Ideally, to facilitate charge transport between the conducting material and the redox material. In fact, an important characteristic of the present invention is that the particles are porous after the coating or loading process. In this respect, the invention is distinguished from other processes where porous particles are coated or loaded to the extent that the particles are no longer porous.

Another object of the present invention is that the redox molecules bearing quinone or hydroquinone groups may exhibit pH-dependent redox properties. Polybenzoxazines contain quinoid and hydroquinone moieties that are providing redox properties. It has also been found the redox activity is higher at low pH and lower at high pH. In many applications, redox activity at high pH is desired.

When the redox function is to enable use of the polymeric and particle- bound redox polybenzoxazine for the use as an electrode immobilized mediator in the reduction of hydrogen peroxide in a biosensor application, the pH should be near the pH values where enzymes producing hydrogen peroxide thrives.

When the redox function is to be used in battery cells, a very low pH is not desired as the cell contents are corrosive to metal parts and low pH.

For these reasons, there is a need to widen the pH-range where the electrode based on the invention may be redox active.

In other aspects of the invention, it is described three methods to increase the pH at which the electrodes based on the invention are redox active. One method is to modify the polybenzoxazine structure by polymerizing polyphenols and polyphenols with ionized and ionizable groups so that these groups are incorporated into the structure. A second method is to embed the redox functional porous particles into an acidic or acidifiable binder matrix. A third method is to coat the electrode with a membrane bearing acidic or acidifiable groups, i.e. an acidic membrane.

With the term “polyphenols” is meant aromatic polymer molecules having two or more hydroxyl groups per aromatic unit.

With the term “acidic binder matrix” is meant a polymeric acid such as polystyrene sulfonic acid, or polyacrylic acid.

With the term “acidifiable binder matrix” is meant salts of polymeric acids that can be turned into acidic binders by treatment with an acid, that is, by ionic exchange.

With the term “membrane” is meant a coating that is permeable to analytes but can serve to protect the electrode from contaminants that cannot permeate the membrane. When the membrane is a polyacid, the membrane changes the pH locally near the electrode. Examples of membranes may be sulfonated polymers and copolymers that can be cast as a membrane but be insuloble during operation conditions. Examples of membranes may be Nation, a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer, or Nexar™, a sulfonated pentablock copolymer (s-PBC). PSSH in the composition PEDOTPSSH may be considered an alternative to Nation in this context as it possesses acid groups and is yet insoluble in water.

Another object is to provide such a method for producing a porous material comprising porous particles with a cross-linked hydroquinone-based polybenzoxazine is that the benzoxazines of formula I, II or III exhibit latent curing at a temperature that is higher than the melting point of the benzoxazines. Thus, the monomer exists as a liquid melt in the temperature range above the melting point but under the onset temperature of polymerization. It is sufficient to heat the material above the threshold or polymerization onset temperature to convert the fluid monomer melt to a cross-linked polybenzoxazine without adding any polymerization initiator. Below this threshold or onset, however, the benzoxazine is stable.

Another object is to provide such a method for producing a porous material comprising porous particles with a cross-linked hydroquinone-based polybenzoxazine that may be performed in one-pot without any solvent, thus providing an easier, cheaper and more sustainable method.

Another object is to provide such a method for producing a porous material by coating porous particles with a cross-linked hydroquinone-based polybenzoxazine having free phenol groups is that the method of the invention enables formation of immobilized redox polymers having good contact with conducting carbon materials by existing as a thin film on the carbons.

Another object is to provide such a composition, comprising the porous material of the invention, designed for electronic circuitry, which may be applied to a substrate or collector by coating or printing.

Another object is to provide such a composition, comprising the porous material of the invention, designed for electrode components in electrochemical cells, which may be applied to a substrate or collector by coating or printing. Another object is to provide such a composition, comprising the porous material of the invention, designed for corrosion protection of metal electrodes due to its high chemical and thermal resistance, for example its stability over a wide pH-range and tolerance to solvents.

Another object is to widen the pH-range of the redox activity of the electrodes and the electrode materials to enable use near the pH of physiological environments and to enable use as redox material in batteries at a pH high enough to prevent metal collector corrosion. With the term “redox activity” is meant that the substance can take part in reactions where the oxidation state is changed. The typical pH range of physiological solutions is 5.5, living organisms and enzymes seldom survives large deviations from this value.

Another object is to provide such a composition, comprising the porous material of the invention, designed for purification of heavy metal contaminated water due to that the porous material functions as an adsorbent for heavy metal ions. This is due to the increased chelation propensity of the amine and hydroxy-heteroatoms by intermolecular bonding to the heavy metal ion via a stable six-membered ring structure.

To achieve at least one of the above objects and also other objects that will be evident from the following description, a porous material having the features defined in claim 1 is provided according to the present inventive concept. A composition including the porous material is provided according to claim 9. A component including the composition is provided according to claim 11. Methods for producing a porous material and a composition are provided according to claims 14 and 19 respectively. Preferred variations to the inventive concept will be evident from the dependent claims.

According to a first aspect there is provided a porous material comprising porous particles coated with a cross-linked polybenzoxazine having free phenol groups, wherein the polybenzoxazine is a polymer product of a monomer selected from the group consisting of formula I, formula II, and formula III:

wherein R ¹ is selected from (Ci-Ci6)alkyl, (Ci-C-io)alkenyl, (Ci- Cio)alkynyl, (C3-C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-Ci6)alkyl and heteroaryl(Ci-Ci6)alkyl. Each of the groups in R ¹ may be unsubstituted or substituted, with one or more R ² , wherein R ² is selected from hydroxy, halogen, cyano, nitro, amino, (Ci-C3)alkyl, (Ci- C3)alkenyl, (Ci-C3)alkynyl, (C3-C6)cycloalkyl, phenyl, heteroaryl, (Ci-C3)acyl, (Ci-C3)alkoxy. Typically, the R ¹ is selected from (Ci-Ci6)alkyl, (Ci-Cio)alkenyl, (Ci-Cio)alkynyl, (C3-C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-Ci6)alkyl and heteroaryl(Ci-Ci6)alkyl, each unsubstituted. The porous material comprising the porous particles comprising pores, with a pore size of at least 4 nm, coated with the cross-linked polybenzoxazine having free phenol groups. The average coating thickness should be less than half the average diameter of most pores in the material so as to leave most pores open after coating. The porous material according to the invention provides an immobilized redox function, as shown for example in Example 7.

The present inventive concept is based on the fact that benzoxazines are small molecules wherein an aromatic ring is fused with an oxazine ring forming a six-membered heterocycle containing two different heteroatoms, one nitrogen and one oxygen. Benzoxazines (Bz) may generally quite easily be synthesized through a Mannich condensation reaction, which involves a phenolic compound, formaldehyde, or para-formaldehyde, and a primary amine. The 1 ,3-benzoxazine isomer, or the monomer of formula I, II or III is especially attractive since it may polymerize through a ring-opening polymerization reaction, wherein a polybenzoxazine with an aza-methylene- phenol is formed.

Further, polybenzoxazines are interesting because of their very advantageous properties, such as excellent mechanical and physical properties. Benzoquinone-based or anthraquinone-based polybenzoxazines are especially interesting, since they comprise a 1,4-hydroquinone/quinone redox couple, that may form a polybenzoxazine with electrochemically tunable surface properties. Thus, the porous particles coated with benzoquinone-based or anthraquinone-based polybenzoxazines according to present inventive concept may provide a novel porous material with immobilized hyrdoquinones/quinones that may function as an immobilized redox functionality within the polymer coated particles as illustrated below.

The term “immobilized redox functionality” or “immobilized redox molecules” or “immobilized redox polymers” means that the radical molecules do not migrate at any electrode potential, or in any electrolyte solvent. This is achieved in the porous material of the present invention, since the polybenzoxazines comprising a redox functionality are cross-linked on the surface of the porous particles. The porous particles may be used in various electrochemical applications because they may accommodate a high charge density due to the large specific area. With the term “redox” means reduction- oxidation, which is a type of chemical reaction in which the oxidation states of atoms are changed. Redox reactions are characterized by the actual or formal transfer of electrons between chemical species, most often with one species e.g. the reducing agent undergoing oxidation i.e. losing electrons, while another species i.e. the oxidizing agent undergoes reduction, i.e. gaining electrons. The chemical species from which the electron is removed is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. The redox process in a chemical cell involves transfer of electrons (or holes) between an electrolyte and the electrodes, when applying a voltage between two conductors that are connected to respective electrode.

Therefore, the porous material according to the present invention comprising porous particles coated with a cross-linked polybenzoxazine having free phenol groups, wherein the polybenzoxazine is a polymer product of a monomer of formula I, II or III has the advantages of low water uptake, no shrinkage during curing of the benzoxazine monomer, low temperature expansion coefficient, low dielectric loss factor, i.e. good dielectric properties, high chemical and thermal resistance, e.g. tolerance to solvents and stability over a wide pH-range and inherent flame attenuation.

Further, important advantages are that low cost starting materials may be used. Even further, the synthesis is simple and easily scalable.

Nevertheless, it has been found that the porous material of the present inventive concept may be formed by a surprisingly easy and efficient method due to the low viscosity of the molten benzoxazine which enables the monomer of formula I, II or III upon heating above an onset temperature for polymerization of the monomer, to form a thin coating on a porous material of immobilized redox polybenzoxazine with a cross-linked network with the regenerated hydroxyl groups from the original starting material hydroquinone, 2,6-dihydroxyanthraquinone or 2,7-dihydroxyanthraquinone. Thus, the method for producing the porous material results in a thin coating of an immobilized redox polymer onto a porous material, e.g. carbon surfaces or silica surfaces, in open porous structures to afford a composite with close vicinity of conducting materials to redox groups while retaining the retain porosity of the porous carbon matrix. Further, the polybenzoxazine may be a polymer product of a monomer of formula I or formula II:

I II

Further, the polybenzoxazine may be a polymer product of a monomer of formula I:

I

R ¹ may be selected from (Ci-Ci2)alkyl, (Ci-C-io)alkenyl, (Ci-C-io)alkynyl, (C3-C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci- C3)alkyl and heteroaryl(Ci-C3)alkyl.

The term “alkyl” means both straight and branched chain saturated hydrocarbon groups as well as cyclic hydrocarbons. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, iso- propyl, n-butyl, t- butyl, /so-butyl, and sec-butyl groups. In the present application the term “(Ci- Ci6)alkyl” means an alkyl chain, straight or branched, comprising between 1- 16 carbon atoms. Examples of unbranched alkyl groups are methyl, ethyl, n- propyl, and n-butyl groups. More specifically the alkyl group may be dodecyl. Among branched alkyl groups, there may be mentioned iso- propyl, f-butyl, /so-butyl, and sec-butyl groups. Further, there is the option that the alkyl groups of the present invention are cyclic alkyl or cycloalkyl groups, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl. In the present application the term “(C3-C6)cycloalkyl” means a cyclic hydrocarbon comprising between 3-6 carbon atoms. The term “alkenyl” means an alkyl group containing one of more double bonds. Alkenyls of the present invention may be cis- or trans- configured.

The term “alkynyl” means an alkyl group containing one of more triple bonds.

The terms “aryl” and “heteroaryl” means a group containing an aromatic or heteroaromatic moiety, where the aromatic or heteroaromatic moiety is directly attached to the structural motif in question. Examples of aryl group include, but are not limited to, phenyl, naphthyl, anthryl, phenanthrenyl or pyrenyl. In the present application the term “(C6-C24)aryl” means an aromatic group comprising between 6-24 carbon atoms, thus ranging from phenyl comprising 6 carbon atoms to larger fused aromatic systems, for example coronene comprising 24 carbon atoms. Examples of heteroaryl groups include, but are not limited to, five- to twelve-membered heterocyclic groups containing one or more heteroatoms selected from oxygen, nitrogen and sulfur. More specific examples of heteroaryl groups include, but are not limited to, pyridinyl, pyrimidinyl, pyrazinyl, pyrrolyl, thienyl, thiophenyl, furanyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl and fused analogues thereof.

The term “heterocycloalkyl” means a cyclic group of carbon atoms wherein from one to three of the carbon atoms is/are replaced by one or more heteroatoms independently selected from nitrogen, oxygen, and sulfur. Examples of heterocycloalkyl groups include, but are not limited to, tetrahydrofuranyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, dioxanyl, and the like. Examples of a 3 to 6- membered heterocycloalkyl groups include, tetrahydrofuranyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, dioxanyl, and the like. The term “alkoxy” means the group O-alkyl, where “alkyl” is used as described above. Examples of alkoxy groups include, but are not limited to, methoxy and ethoxy groups. Other examples include propoxy and butoxy, such as iso- propoxy, n-propoxy, ferf-butoxy, iso- butoxy and sec-butoxy. The oxygen atom is directly attached to the structural motif in question. Similarly, the terms “aryloxy” and “heteroaryloxy” means the group O-aryl and O-heteroaryl, respectively, where “aryl” and “heteroaryl” are used as described herein.

The term “halogen” is a halogen atom, which may be selected from F, Br, Cl and I.

Further, in embodiments of the present invention, when alkyls are included, such as when R ¹ represents alkyl it may be a methyl, ethyl, n-propyl, iso- propyl, n-butyl, sec-butyl, /so-butyl, fe/f-butyl, n-pentyl, n-hexyl, n-octyl, n- nonane, n-decane, n-undecane, n-dodecane, n-hexadecane, n-octadecane, n-icosane, or n-tetracosane.

Further, in the present invention, when aryls are included, such as when R ¹ represents aryl it may be phenyl, naphthyl, or anthryl, such as phenyl.

Furthermore, in the present invention, when heteroaryls are included, such as when R ¹ represents heteroaryl it may be pyridinyl, pyrimidinyl, pyrazinyl, pyrrolyl, thienyl, thiophenyl, furanyl, imidazolyl, oxazolyl, thiazolyl, or thiadiazolyl.

According to one embodiment of this aspect of the invention, R ¹ is selected from phenyl, a 5-6-membered heteroaryl and (Ci-Ci2)alkyl, such as phenyl, furfuryl and (Ci-Ci2)alkyl, such as phenyl, furfuryl and (Ci-Ce)alkyl, such as phenyl and furfuryl. By introducing a different R ¹ -substituents in the benzoxazine, the properties of the resulting polybenzoxazine-based porous material may be tailored to suit specific needs. For example, when R ¹ is a phenyl or a furfuryl, provides with stable redox molecules. By using (Ci- Ci2)alkyl as R ¹ -substituent there is the possibility to fine tune the material even further, since long alkyl chains may alter the viscosity and melting point of the monomer and also the curing temperature for formation of the corresponding polymer.

According to another embodiment of this aspect, the polybenzoxazine may be a polymer product of a monomer selected from the group consisting of formula I, formula II, and formula III of the present invention, and a molecule comprising at least one phenol group, preferably the molecule comprises more than one phenol group and optionally at least one ionic or ionizable functional group. In other words, the polybenzoxazine may be a polymer, incorporating phenol units obtained by the addition of phenols to the monomer mixture, wherein the monomer is selected from the group consisting of formula I, formula II, and formula III of the present invention, preferably polyphenols as the main objective is to obtain redox activity.

With the term “phenol group" is meant an aromatic molecule comprising two or more hydroxyl groups per molecule. A phenol group may also be considered being a hydroxy aromatic compound.

In one embodiment the porous material according to the present invention is comprising porous particles coated with a cross-linked polybenzoxazine having free phenol groups, wherein the polybenzoxazine may be formed or polymerized in the presence of molecules comprising at least one phenol group, preferably more than one phenol group and optionally at least one ionic or ionizable functional group, or other functional groups residing on a hydroxy aromatic compound.

Examples of molecules comprising at least one phenol group may be Rhodizonic acid, tetrahydroxyquinone, purpurin and naringenin. Examples of polymer molecules comprising two or more hydroxyl groups may be polyphenols, tannic acid and lignin.

With the term “ionic or ionizable functional group” means mainly free acids, or salts of acids, that is anions, salts of anions. A quaternized onium compound is an example of a cationic compound. An amine that can be ionized upon protonation is another example. Other functional groups residing on a hydroxy aromatic compound may be groups that are polymerizable by other mechanisms, for example (Ci-Cio)alkyl groups, bulky (Ci-Cio)alkyl groups, perfluoro(Ci-Cio)alkyl groups, perfluoro(Ci-Cio)alkyl acids, carboxylic acids or phosphonic acids. The hydroxy group, as well as the other functional groups residing on the hydroxy aromatic compound, may be activating groups. The activating groups may be primarily directing towards substitution at the orto- or para-position on the aromatic ring. Examples of phenols with polymerizable groups may be vinyl phenol, or alkoxyphenols, such as butoxyphenol or tert-butoxyphenol. The molecule comprising at least one phenol group may be selected from phenol, 1 ,2-dihydroxybenzene (catechol), 1 ,3-dihydroxybenzene (resorcinol), 1 ,4-dihydroxybenzene hydroquinone), benzene-1 ,2, 3-triol, 1,2,4- benzenetriol (hydroxyhydro-quinone), benzene-1 ,3, 5-triol, 2-hydroxy-1 ,4- naphthoquinone, 1 ,2-dihydroxyanthraquinone (Alizarin), 1,4- dihydroxyanthraquinone, 3, 4-di hydroxy-9, 10-dioxo-9, 10-dihydroanthracene-2- sulfonic acid (Alizarinsulfonate), 3,4-dihydroxy-9,10-dioxo-2- anthracenesulfonic acid sodium salt (sodium alizarinsulfonate or alizarin S red having a sulfonic acid or sulfonate), gallic acid (trihydroxybenzene with a carboxylic group). Phenol groups may initiate the polymerization of benzoxazines. This reaction incorporates the phenol molecule or fragment into the polybenzoxazine. Thus, a polymer of polybenzoxazine onto the phenol may be formed. In particular, alizarin and sulphonated alizarin are quinone-resembling polyphenols, wherein their hydroxy groups, if not involved in initiating the polymerization reaction, will still be present in the polybenzoxazine, i.e. the polybenzoxazine having free phenol groups, and their redox properties will contribute to the redox activity of the porous material. Further, sulphonated alizarin will also contribute with a built-in acidity in the polybenzoxazine so that an external or added solution or layer comprising binders or top coatings will be redundant. Normally, especially in chain polymerization, the amount of initiator is typically low, max a few molar %. According to the present invention this may be different, such that there may be a good compatibility between phenol chemistry and benzoxazine chemistry. Thus, typically the amount of initiator molecule may be 30 mole% or less.

The porous particles may have a specific surface area in the range of 1 - 2600 m ² /g, preferably 5 - 2500 m ² /g, preferably 25 - 2000 m ² /g.

The porous particles may be small particles, such as powder, or larger granules, such as granular activated carbon or granulated activated carbon (GAC). GAC is common to use in water purification. In this case, pieces, granules, balls or beads of GAC particles may be from a few millimeters to a few millimeters large. Apart from the size of the particles, there are no major differences from activated carbon in powder form. On the other hand, it may be more tricky to obtain a homogeneous wetting of the particles if the volume of the monomer melt is small. To enable application of low loadings of benzoxazine monomers, monomers with high melting point may be used to achieve a homogenous distribution of monomers among porous particles or porous granules. Further, impregnation of the porous material can be assisted by a solvent. Some advantages from using solvent assisted distribution of monomers between carbon particles or granules may be that it may be easier to obtain a more even distribution between granules and sufficient wetting if the monomer melt is not the only liquid, especially when using a monomer with too high a melting point or too high a melt viscosity, or when the granules are so large that the volume of the melt does not fill gaps between granules, or in the event of wanting to load a smaller volume of monomer into the activated carbon or granules, and that the volume of melt thus becomes smaller.

The term “specific surface area (SSA)” is a property of solids defined as the total surface area of a material per unit of mass. It is a physical value that can be used to determine the type and properties of a material, e.g. soil or snow, and has a particular importance for adsorption, heterogeneous catalysis, and reactions on surfaces. The specific surface area may be measured by adsorption and has the advantage that the surface of fine structures and deep texture on the particles may be measured. However, the results may differ distinctly depending on the substance which is adsorbed.

The porous particles may be fine powders or granulated forms of porous matter. Further, the porous particles may be selected from activated carbon, carbon black, graphite nanofiber, carbon nanotube, and silica. Preferably, the porous particles are activated carbon or carbon black.

The term “porous material” or “porous particle” may be defined as a class of materials with low density and large specific surface area (SSA). Porous materials may be microporous, mesoporous or macroporous. A mesoporous material is a material containing pores with diameters that ranges from 2 nm to 50 nm. Correspondingly, microporous material are materials having pores smaller than 2 nm in diameter and macroporous materials are material having pores larger than 50 nm in diameter. The porous material of the present invention may preferably be mesoporous or macroporous. The porous material may have a mix of different pore sizes, wherein micropores may also be present. However, if there are too many micropores in the porous particles the pore might risk being clogged or blocked when coated with benzoxazine polymer. Thus, mesopores must be present in the porous material to enable both a large surface area (due to smaller pores) and the possibility for ion transport (in case of larger pores). Preferably the pore size may be at least 4 nm.

The term “carbon materials” or “carbon” means carbon-based materials which may be classified according to their C-C bonding, based on sp, sp ² or sp ³ hybrid orbitals. Carbon materials are group of porous and non-porous materials, wherein the surface area, pore size, and pore shape may strongly influence the properties of e.g. the supported polymer. Activated carbon is an important group of mesoporous materials, which has direct applications in energy storage devices. Mesoporous carbon has porosity within the mesopore range and this significantly increases the specific surface area. The carbon materials may be selected from activated carbon, carbon black, diamond, graphite, fullerenes, carbon nanotubes, graphene and carbynes, wherein each member is unique in terms of structure and texture. However, it is an important aspect for the present invention that the carbon material is porous, i.e. that it has a pore size of at least 4 nm and that the pores of the porous material are not completely blocked or filled by the coating, i.e. the average coating thickness or loading should be less than half the average diameter of most pores in the material so as to leave most pores open after coating or loading. Due to their ability to accept foreign atoms or compounds into their structures, various functions of the carbon materials may be improved. Thus, the surface chemistry of carbon materials, acting as a support, may be used to a tailor the properties of the anchored active species.

“Activated carbon” or “activated charcoal” is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Due to its high degree of microporosity, one gram of activated carbon may have a specific surface area in excess of 3,000 m ² /g. Further, activated carbon is also a common mesoporous material which is typically composed of a carbon framework with both mesoporosity and microporosity depending on the conditions under which it was synthesized. Carbon black (CB) is one of the most common conducting additives and it has a higher electron conductivity compared to activated carbon (AC).

Since the conductivity differ among carbon materials, electroconductive carbon black (ECCB) may be most relevant in this inventive concept. ECCB improves electrical conductivity and electromagnetic or thermo-conductive characteristics of plastic materials and rubbers. Electroconductive carbon blacks contain plenty of graphitic structures and exist as elongated chain-like aggregate structures, while activated carbons have lower conductivity.

Carbon black predominantly includes a conductive type of carbon, which combines an extremely high specific surface and extensively developed structure, microporosity to macroporosity. At the same time, ECCB consists of primary carbon particles and boasts a high degree of aggregation. Carbon black's grouping facilitates the formation of a conductive structure in plastics, rubbers and other composites. ECCB may modify the electrical conductivity of nearly all types of plastic materials by adding a relatively low volume of carbon black.

In another embodiment, the porous particles may be silica.

The term “silica” or “silicon dioxide” means an oxide of silicon with the chemical formula S1O2, which may commonly be found in nature as quartz. Silica is a typical mesoporous material that has pores of similar size. Further, silica is a non-conducting material. Thus, the use of silica in the porous material of the present invention may be advantageous in applications wherein the porous material does not need to be conducting, but where the redox material is preferentially immobilized on particles to serve as internal reference, as mediator in electrochemical reactions, and in label-free electrochemical sensors, for example. Electrochemical sensors are a class of chemical sensors in which an electrode is used as a transducer element in the presence of an analyte and they may use several properties to detect various parameters, such as physical, chemical, or biological parameters. A chemical sensor is a self-contained analytical device that can provide information about the chemical composition of its environment, such as a liquid or a gas phase. The information is provided in the form of a measurable physical signal that is correlated with the concentration of a certain chemical species, i.e. as analyte. Two main steps are involved in the functioning of a chemical sensor, namely, recognition and transduction. In the recognition step, analyte molecules interact selectively with receptor molecules or sites included in the structure of the recognition element of the sensor. Accordingly, a characteristic physical parameter varies, and this variation is reported by means of an integrated transducer that generates the output signal. A chemical sensor based on recognition material of biological nature is a biosensor.

According to a second aspect there is provided a composition for coating and/or printing, comprising: a porous material according the first aspect; and a binder. The composition may be considered a coating composition.

According to an embodiment of the second aspect there is provided a composition for coating and/or printing, comprising: a porous material according the first aspect; a solvent and a binder.

The composition may be considered a coating or printing composition. The term “binder” means a substance used to hold particles together after evaporation of the solvent. The solvent imparts fluidity to the composition enabling wet deposition with printing or coating and serves as a dispersing medium for particles of the invention and as a dispersing medium of solvent for binder substances, soluble molecules, binder emulsions or microfibrillar binders. An electrode is formed from the composition by evaporation of the solvent. An electrode material must provide conduits for both electrons and ions for its function and these conduits must both form continuous and interpenetrating networks, and they should conduct electrons and ions with as small resistance as possible. Further, the contact interface area between the electron and ion conduits should be as large as possible, per weight or volume of the electrode material. Redox materials should be located at molecular distance from both phases, that is, at the interface. This is what the invention achieves by coating and immobilizing redox functions at the surface porous electrode particles. The properties and morphology of binder substances is also important. The molecules holding the conducting particles together should not block neither paths for electrons nor ions in the material. Binders in the form of small particles, as provided by emulsified elastomer particles, such as styrene-butadiene rubber (SBR) of polyvinylidene fluoride (PVDF) emulsion, can hold particles together without blocking paths for ion transport, by particles being too large to enter and block internal pores within particles. Fibrous materials, such as nano- and micro fibrillated celluloses are also well suited to form electrode binders as the space between fibers can provide paths for ion transport and large fibers cannot enter and block internal pores. Particulate and fibrous binders can also allow for direct contact between particles to provide electron conducting paths throughout the electrode. Binders form typical polymer solutions, on the other hand, can result in the blocking of ion channels in pores and can create coatings that can prevent electron conductivity between particles. There are polymer solutions that can be used as binders, such as PVDF or PVDF copolymers since upon heating, they rearrange into a porous fibrillar network, upon crystallization and this fibrous fibrillar network permits and provide transport paths for ions. In the case of emulsion of polymer particles, such as SBR and PVDF, and for nano- or micro fibrillated celluloses, the solvent is typically water. In the case of PVDF solutions, the solvents are typically organic solvents of the type, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and cyclic lactone such as butyrolactone, carbonates such as diethyl carbonate, ether ester, ether ester alcohols etc.

The binder may be selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride copolymers, poly(3,4-ethylenedioxy- thiophene)-polystyrene sulfonate (PEDOT-PSS) or poly(3,4-ethylenedioxy- thiophene)-polystyrene sulfonic acid (PEDOT-PSSH), butadiene rubber, styrene-butadiene rubber, polysaccharide binders including nano- or micro- fibrillated cellulose, carboxymethylated derivates, cellulose derivatives, or alginates. The organic solvent may be selected from dimethyl glutarate, dimethyl adipate, dimethyl succinate, DBE-3, DBE-9, dipropylene glycol diacetate or dimethyl sulfoxide (DMSO), or mixtures thereof. Preferably the solvent and the binder may be an emulsion of polyvinylidene fluoride in water, or a mixture of polyvinylidene fluoride and DBE-9. The binder may also be divided into water-based binders and organic solvent-based binders. The water-based binders may be selected from the group consisting of water- based emulsions of polyvinylidene fluoride or polyvinylidene fluoride copolymers, butadiene-based rubber, or the groups of water-soluble polymers or water dispersible fiber materials, polysaccharide binders, including nano- or micro-fibrillated cellulose, carboxymethylated derivates, cellulose derivatives, or alginates. The organic solvent-based binders may be selected from the group consisting of polyvinylidene fluoride, copolymers of polyvinylidene fluoride in dimethyl glutarate and/or dimethyl succinate. Thus, polyvinylidene fluoride or copolymers of polyvinylidene fluoride may be dissolved in organic solvents or binders, including ketones, such as acetone; esters, such as ethyl acetate, dimethyl glutarate or dimethyl succinate; dibasic esters, such as DBE-3 (a mixture of dimethyl adipate and dimethyl glutarate) or DBE-9 (a mixture of dimethyl glutarate and dimethyl succinate); ether esters, such as dipropylene glycol diacetate. Water-based binders are advantageous due to that they are more environmentally sustainable, whereas organic solvent-based binders may be advantageous for coating or printing.

Polyvinylidene fluoride (PVDF) is especially valuable since it has the advantage of being resistant to solvents, acids and hydrocarbons. As a binder component, PVDF is very well functioning in combination with the carbon electrode in super capacitors and for other electrochemical applications. Styrene-butadiene or styrene-butadiene rubber (SBR) is a material with good abrasion resistance and good aging stability. SBR in combination with carboxym ethyl cellulose may also be used as a water-based alternative for PVDF in applications such as a binder in e.g. battery electrodes.

The composition according to the second aspect may further comprise an electrically conducting additive selected from carbon black, graphite nanofiber, carbon nanotube and poly(3,4-ethylenedioxythiophene)- polystyrene sulfonate (PEDOT-PSS) or poly(3,4-ethylenedioxy-thiophene)- polystyrene sulfonic acid (PEDOT-PSSH). PEDOT-PSS or PEDOT-PSSH may act as both a binder and a conductivity booster.

The term “electrically conducting additive” or “electrically conductive additive” may be carbon based additives that form a percolating network for electron transport in the electrode layer which largely improves the electrode conductivity.

An advantage of using activated carbon in combination with the low viscosity monomer is that the mixing performed under agitation enables wetting and spreading of the molten benzoxazine onto the carbon surface resulting in an even distribution of the material. The spread of the benzoxazine enables formation of a coating onto the surface of a porous carbon material. After wetting of the molten benzoxazine, the particles are still porous with an average coating thickness of 1-5 nm, which is approximately the tunneling distance of electrons. Preferably the particles have an average coating thickness of less than 2 nm. Assuming an even coating is obtained when porous particles are coated with benzoxazine polymer, the thicker the layer the smaller pores will become blocked and the specific surface area will decrease. However, as long as there are open pores the properties of the redox material will remain. The pore size of carbon materials may vary a lot, which is why it is a preferred porous material. Thus, the average coating thickness should be less than half the diameter of most pores in the material so as to leave most pores open after coating.

The composition according to the second aspect may further comprise one or more additional agents selected from the group of: initiator molecules, processing aid agents, for example rheology and surface tesion modifying agents and compatibilizing agents. These additional agents are providing specific tailored properties of the composition or are added in view to facilitate the method of producing the composition.

According to a third aspect there is provided a printable or coatable ink comprising a composition according to the second aspect. This has the advantage that the porous material composition may easily be provided on different surfaces and may for example be used in printed electronics. Today, there are no printable inks with a redox functionality on the market, to the best of the inventor’s knowledge.

According to a fourth aspect there is provided a component, such as an electrode component, comprising a conductor coated with a composition according to the second aspect. The component may further comprise an electrolyte, wherein the porous material according to the first aspect is part of the electrode component. The term “component” refers to a component that may be used in or part of an electric circuit. The term “component” in the present invention may have various meanings. With respect to the present invention, an electrochemical cell may be a component in a device or system, an electrode may be a component in an electrochemical cell, a material may be a component in an electrode. According to one example the component is an electrochemical cell used for providing current in an electric circuit. According to one embodiment of the fourth aspect of the invention, the component may be further coated with an acidic permeable coating comprising an insoluble network of a polymeric acid, preferably the polymeric acid is Nafion.

“Further coated” in regard to this aspect means that an addition coating or layer is being applied after the electrode coating has been deposited and cured, in order to protect the electrode from contaminants that cannot permeate the further coating. The further coating may be a membrane that is being applied on top of the coated porous particles. The membrane may comprise acidic or acidifiable groups, i.e. an acidic membrane.

The term “acidic permeable” means that it allows acids to permeate or pass through its structure. The polybenzoxazine-decorated porous carbon particles may form a base for printable and coatable compositions as non- coated carbon particles. This is because the pore size does practically not change after coating, which is important for the properties and function of the porous material.

According to a fifth aspect there is provided a method for producing a porous material by coating porous particles with a cross-linked hydroquinone- based polybenzoxazine having free phenol groups, comprising the steps of: a. providing a mixture of porous particles and a benzoxazine monomer selected from the group consisting of formula I, formula II, and formula III: wherein R ¹ is selected from (Ci-Ci6)alkyl, (Ci-C-io)alkenyl, (Ci- Cio)alkynyl, (C3-C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-Ci6)alkyl and heteroaryl(Ci-Ci6)alkyl; b. heating the mixture of porous particles and the benzoxazine monomer of formula I or formula II at a temperature above a melting point of the benzoxazine monomer of formula I or formula II and below an onset temperature of thermal polymerization of the benzoxazine monomer of formula I or formula II under agitation; and c. raising the temperature above the onset temperature of thermal polymerization of the benzoxazine monomer of formula I or formula II, thereby forming the porous material by thermal ring-opening, curing and cross-linking of the benzoxazine monomer of formula I or formula II under agitation.

In one embodiment, the method according to the fifth aspect, the pores may be provided with a pore size of at least 4 nm.

Each of the groups in R ¹ may in turn be unsubstituted or substituted, with one or more R ² , wherein R ² is selected from hydroxy, halogen, cyano, nitro, amino, (Ci-C3)alkyl, (Ci-C3)alkenyl, (Ci-C3)alkynyl, (C3-C6)cycloalkyl, phenyl, heteroaryl, (Ci-C3)acyl, (Ci-C3)alkoxy. Typically, the R ¹ is selected from (Ci-Ci6)alkyl, (Ci-Cio)alkenyl, (Ci-Cio)alkynyl, (C3-C6)cycloalkyl, 3 to 6- membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-Ci6)alkyl and heteroaryl(Ci-Ci6)alkyl, each unsubstituted. In general, features of this aspect of the invention provide similar advantages as discussed above in relation to the first aspect of the invention. Consequently, said advantages will not be repeated in order to avoid undue repetition. However, an advantage of step a is that cheap starting materials may be used. The synthesis of the monomer is a Mannich reaction that normally proceed with high product yields. An advantage during step b, is the low viscosity and the agitation enables wetting and spreading of the molten benzoxazine onto the carbon surface resulting in an even distribution of the material. The spread of the benzoxazine enables formation of a coating onto the surface of a porous carbon material without clogging of the pores, i.e. there is basically no change in pore size of the provided porous particles.

A further advantage is that the monomer is stable under an onset temperature for polymerization. Thus, step c provides the advantage of the monomer polymerizes without an initiator and just by raising the temperature above an onset temperature where the monomer is cured, i.e. the polymer forms a cross-linked structure on the surface of the porous particles and the phenol hydroxy groups are regenerated forming the redox functionality of the formed porous material.

The method according to the fifth aspect, wherein the benzoxazine monomer selected from the group consisting of formula I, formula II, and formula III may be produced by reacting paraformaldehyde, R ¹ NH2 and hydroquinone for forming the monomer of formula I; 2,6- dihydroxyanthraquinone for forming the monomer of formula II; and 2,7- dihydroxyanthraquinone for forming the monomer of formula III. The method may be a one-pot process. The term “one-pot process” or “one-pot synthesis” is a strategy to improve the efficiency of a chemical reaction whereby a reactant is subjected to successive chemical reactions in just one reactor.

This is much desired, because avoiding a lengthy separation process and purification of the intermediate chemical compounds may save time and resources while increasing the chemical yield.

Further, steps a, b, and c may be performed without the addition of any solvent. Thus, method of the present invention has the advantage of being a simple process, less hazardous and cheap process, that may be carried out in e.g. a kiln reactor or any type of reactor wherein the reaction may be scaled. However, a good purification of the monomer may be obtained by using a solvent, such as dichloromethane, during the reaction since the biproduct formed precipitates from the solution and may then be separated from the reaction mixture by e.g. filtration.

The method according to the fifth aspect, wherein the melting point of the benzoxazine monomer may be lower than the polymerization onset temperature by at least 10 °C, preferably by at least 15 °C or by at least 20 °C. The wider process window, to a certain extent, the better, i.e. the window between the melting point of the monomer and curing temperature for the formation of the corresponding polymer. Most important is that the polymerization process does not start, i.e. that the on-set temperature has not been reached, before the benzoxazine monomer has had time to spread over the whole surface of the porous particle.

Further, the melting point of the benzoxazine monomer may be in the range of from 20 to 180 °C, such as 60 to 160 °C. Even further, the onset temperature of thermal polymerization of the benzoxazine monomer may be in the range of from 150 to 300 °C, 170 to 300 °C, such as 200 to 300 °C. Thus, as mentioned above, the monomer is stable at its melting point, below an onset temperature of thermal polymerization but spontaneously polymerizes above a specific onset temperature.

In one embodiment, the benzoxazine monomer may be of formula I or formula II

II

In another embodiment, the benzoxazine monomer may be of formula

According to a sixth aspect there is provided a method for producing a composition for coating and/or printing, comprising the method according to the fifth aspect, which further comprises the step of: d. mixing said porous material with a binder dissolved in a water-based solvent or an organic solvent. An advantage with using water-based solvent may be that the method is more environmentally friendly. The use of low-boiling organic solvents may on the other hand be more easily removed from the composition.

The method further comprising the step of: e. adding an electrically conducting additive to the resulting composition of step d or to the porous material resulting from step c.

The coated porous material may be conducting in itself. However, by adding a conductive additive the resistance in the material may be further decreased due to the thin layer of polybenzoxazine coating onto the porous particles. The amount benzoxazine monomer that is added to the porous particles should not be too much so that the particles become wet after coating, which can lead to clogging during polymerization. Therefore, the amount of benzoxazine monomer is estimated so that the material is still in powder form after coating. The layer average thickness of the polybenzoxazine coating onto the porous particles is calculated as an average by making the assumption that the porous material has the density of 1 kg/m ³ . Further, the average thickness is then calculated by dividing the surface volume of the porous particle with the assumed density. The coating thickness of the thin layer of polybenzoxazine coating onto the porous particles may be in average 1-5 nm, preferably less than 5 nm, less than 4 nm, less than 3 nm, less than 2 nm, or less than 1 nm. Most preferably the average coating thickness is less than 2 nm, less than 1 nm or less than 0.5 nm. Preferably the average coating thickness is less than half the average diameter of most pores in the material so as to leave most pores open after coating.

According to a seventh aspect there is provided a use of the composition according to the second aspect or a component according to the fourth aspect in a sensor. There is also provided a use of a component according to the fourth aspect in an electrode component or an electrochemical cell, such as an energy storage device, a battery, a super capacitor, a printed electrochromic cell, or a transistor.

In a further aspect of the present invention there is provided a method of manufacturing an electronic circuitry comprising the steps of: a. providing a substrate; b. providing a circuitry on said substrate by means of printing, wherein said step of providing said circuitry comprises coating a portion of said circuitry with the composition according to the second aspect.

This method of manufacturing an electronic circuitry is really beneficial since cheap materials and simple apparatus may be used. Further, the electronic circuitry may be applied in a precise manner due to the fact that it may be printed. The printing or coating techniques that may be used for the deposition on to a substrate of a defined layer of the composition according to the second aspect may be, e.g. screen printing, flexo printing, gravure printing, offset printing or bar-coating. According to one example the printable ink is suitable for one or more of screen printing, flexo printing, gravure printing, offset printing, bar-coating and ink-jet printing, the list is non- exhaustive. According to one example the printable ink is suitable for one or more of screen printing, flexo printing, gravure printing, offset printing bar coating but not suitable for e.g. ink-jet printing due to the large particle size or rheological properties.

In yet a further aspect there is provided a component comprising a conductor coated with a porous material according to the first aspect, and further comprising an electrically conducting additive selected from carbon black, graphite nanofiber, carbon nanotube and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate or sulfonic acid, such as carbon black. The component may be an electrode component or an electrochemical cell, such as an energy storage device, a battery, a super capacitor, a sensor, a printed electrochromic cell, or a transistor, or combinations thereof.

The term “electrode component” refers to a self-contained electrode or an electrode provided on a carrier for use e.g. in an electrical circuit and/or an electrochemical cell.

According to one example the electrochemical cell is provided in a circuit and serves the purpose of storing energy, releasing energy, as well as acting as a sensor where the sensor reading is made based on the potential difference between the anode and the cathode and varies for example in response to the presence of e.g. biomolecules or metal ions in the vicinity of the electrochemical cell.

In a further aspect of the present invention there is provided a method of producing an electrode comprising the steps of proving a carrier and depositing a composition according to the second aspect on said carrier. The carrier may be a solid substrate which comprises a non-conducting or conducting material. The carrier may typically be in a sheet-like or plate-like form.

In another aspect, there is provided an energy storage device, such as a battery or a super capacitor, comprising and electrolyte optionally arranged in a matrix such as cellulose or other porous material (e.g. via absorption). Said electrolyte is arranged in ionic contact with a pair of electrodes. The ionic contact may be provided by the electrolyte being sandwiched between the electrodes. Alternatively, the electrodes may e.g. be arranged side by side on the same substrate and separated by a gap, and the electrolyte bridges said gap and thereby provides an ionic connection. A respective conductor is electronically connected to each one of the electrodes, for conducting electrons/holes to the respective electrodes. Each conductor is preferably in direct physical contact with a respective portion of the electrode, which portion may be a minor portion of the electrode surface area such as 5 % thereof, or a major portion of the surface area such as 100 % thereof or any value in between 5% and 100%. When the electrolyte is sandwiched between the electrodes, the electrodes may be sandwiched between the pair of conductors. For all embodiments, at least one of said electrodes comprises a porous material according the first aspect or a composition according to the second aspect.

By applying a potential difference between the pair of electrodes, the porous material according the first aspect or the composition according to the second aspect may be charged or discharged via an interaction with the electrolyte, a redox reaction is an example of such an interaction.

In an even further aspect, there is provided a method for removal of heavy metal ions from heavy metal contaminated water, comprising the steps of: a. contacting heavy metal contaminated water with a porous material according the first aspect of the present invention.

This has the advantage of being a low-cost method that avoids release of toxic solvent, compared to methods know in the prior art. Further, the porous material used in the method of absorbing heavy metals from water may further be re-generated due to its redox functionality. Thus, the heavy metal ion may be expelled or desorbed from the surface of the porous material.

In another aspect there is provided a use of a porous material according to the first aspect for removal of heavy metal ions from heavy metal contaminated water. Due to the chelating effect of the amine nitrogen and the hydroxy oxygen of the polybenzoxazine in the porous material may act as a sorbent for heavy metal ions by intermolecular binding.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person will realize that different features of the present invention may be combined to create variants other than those described in the following, however the present invention is defined by the appended claims. Features of one aspect may be relevant to anyone of the other aspects.

Brief description of the drawings

The above and other aspects of the present inventive concept will now be described in more detail, with reference to appended drawings showing variants of the present inventive concept. The figures should not be considered limiting the inventive concept, instead they are used for explaining and understanding the inventive concept.

As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and are thus provided to illustrate the general structures of variants of the present inventive concept.

Figure 1 shows a schematic illustration of a method for producing a porous material.

Figure 2 illustrates a block scheme of a method for producing a porous material.

Figure 3 illustrates a block scheme of a method for producing a composition comprising a porous material and a binder.

Figure 4 illustrates a block scheme of a method for producing a composition comprising a porous material, a binder and an electronically conducting additive.

Figure 5 shows a cyclic voltammogram of a carbon black-based porous material. Figure 6 shows a cyclic voltammogram of an activated carbon-based porous material.

Figure 7 shows a schematic illustration of a method for producing a composition for coating an electrode.

Figure 8 schematically illustrates how a composition comprising a porous material may be applied by a coating/printing process for manufacturing of electronic circuitries.

Figure 9 illustrates a block scheme of a method for manufacturing of an electronic circuitry.

Figure 10 illustrates a block scheme of a method for removal of heavy metal ions from heavy metal contaminated water.

Figure 11 shows a schematic illustration of an electrochemical cell, such as an energy storage device.

Detailed description of the invention

The present inventive concept will now be described more fully hereinafter with reference to the accompanying drawing, in which preferred variants of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the variants set forth herein; rather, these variants are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person. Although individual features may be included in different variants, these may possibly be combined in other ways, and the inclusion in different variants does not imply that a combination of features is not feasible. In addition, singular references do not exclude a plurality. In the context of the present invention, the terms “a”, “an” does not preclude a plurality.

The present invention discloses a novel porous material 1 and a method 100 for producing the porous material 1 and methods 200 and 300 for producing composition 5 to enable manufacturing of a component 9 comprising a conductor 10 or printable ink 8 that may be used in a vast number of applications, including in electrical storage devices 20, biological sensors 50 or printed circuitries 60.

The porous material described herein may be defined as an immobilized redox material, especially for a composition 5 comprising a porous material 1 , which is formed via a simple one-pot synthesis with readily attainable and cheap starting materials.

In figure 1 and figure 2 a novel surprisingly easy and efficient method 100 for producing the novel porous material 1 is illustrated schematically. The method 100 may be performed as a one-pot synthesis, wherein porous particles 2 are provided 110 in a mixture of monomer 4, which may be produced in situ in the reaction vessel by reaction of a hydroquinone, formaldehyde and a primary amine, forming the 4 without the need of a solvent. The mixture of porous particles 2 and monomer 4 are heated 120 at reflux, wherein the provided or formed monomer 4 is in the form of a melt or low viscosity fluid, which easily penetrates the pores of the porous particles 2 under agitation of the reaction mixture. When the melt of monomer 4 has penetrated the porous particles 2 the reaction temperature is raised 130 to a temperature above the curing of the polymer. Thus, the benzoxazine (Bz) monomer 4 forms a cross-linked polybenzoxazine (PBz) 3 on the surface of the porous particles 2, thereby the hydroquinone redox functionality of the formed porous material 1 is regenerated. More specifically, a schematic illustration of the synthesis of the porous material 1 is shown in scheme 1. Examples 1, 2 and 3 describe the preparation of porous material 1, wherein the primary amine is furfurylamine and the porous particles are carbon black (CB) and activated carbon (AC), respectively. Bz is added in an amount corresponding to an average coating thickness of 1 nm calculated over the whole available surface of the carbon surface, that is approximately 1 mg / m ² carbon surface assuming a density of 1 g / cm ³ of the monomer. For an AC with the specific surface area of 1000 m ³ / g this would translate into a Bz loading of 1 g / g AC. The average thickness of 1 nm is in the relevant range since this is comparable with the tunneling distance of electrons. To enable application of low loadings of benzoxazine monomers, the use of monomers with high melting point, and to achieve a homogenous distribution of monomers among porous particles or porous granules, impregnation of the porous material can be assisted by a solvent. To enable impregnation of porous particles, the process can be assisted by application of a vacuum to remove air in the pores before the fluid is added. The solvent serves to provide a free liquid phase outside of the particles during impregnation to enable a homogeneous distribution of monomer among particles where otherwise the volume of a monomer melt would be soaked into the particles before all particles are wet by the melt. The use of a solvent to assist distribution and impregnation of the porous particles is described in examples 1a, 3a and 3b, and the use of a granular porous material is described in example 5. Scheme 1.

The present invention solves the preparation of the porous material 1 in a really clever and easy way but it is important that the step b of heating 120 the mixture of the benzoxazine monomer 4, e.g. of formula I, II or III, and the porous material 1 , such as activated carbon, carbon black, graphite nanofiber, carbon nanotube, and silica, takes place above the melting point of the benzoxazine monomer 4, but under the temperature of thermal polymerization of the polybenzoxazine 3. The melting point may typically be in a range from 20 to 180 °C, such as 60 to 160 °C. The most important is that it is at least 10 °C below the polymerization onset temperature. Further, in treatment step c, the temperature is raised 130 above the onset temperature of the polymerization, which may be in the range from 150 to 300 °C, such as 170 to 300 °C, or 200 to 300 °C. Thus, the porous material 1 is stable against high temperatures and it is resistant against strong acids.

A novel composition 5 comprising the porous material 1 may be produced according to method 200 as shown in figure 3. Thus, the porous material may be prepared as presented above via steps 210, 220 and 230, correspondingly. Method 200 then comprises a further step d of mixing 240 the porous material 1 with a binder 6, such as polyvinylidene fluoride, polyvinylidene fluoride copolymers, PEDOT-PSS, butadiene rubber, styrene- butadiene rubber, polysaccharide binders including nano- or microfibrillated cellulose, carboxym ethylated derivates, cellulose derivatives, or alginates, dimethyl glutarate, dimethyl adipate, dimethyl succinate, DBE-3, DBE-9 or dipropylene glycol diacetate, or mixtures thereof. Preferably the binder 6 is a mixture of polyvinylidene fluoride and DBE-9. Example 6 shows an example wherein composition 5 is mixed with the binder mixture poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) with acetone and DBE-9. The solvent may be any ketone which solves the binder, such as acetone, methyl ethyl ketone (MEK) or cyclohexanone, however in practical use it could be removed. In one example the ratio of porous material FIQ-PBz@CB 1 to binder P(VDF-TrFE) 6 is 70:30 x 5 % in a mixture of Acetone and DBE-9 (1:1). The amount of 5% refers to the dry content P(VDF-TrFE) in the binder solution that is added. The mass ratio of the porous material 1 to binder 6 may be in the range of 1:20 to 1:1.5, preferably 1:10 to 1:5. The ratio 1:20 - 1:1.5 refers to the percentage by weight of binder to electrode material (FIQ- PBz @ AC or CB). Preferably, when the solvent has been removed, the amount of binder in the final composition 5 is at most 35 wt%, or at most 20 wt%, so as to not risk clogging of the pores. When using binder 6 in the form of particles, such as butadiene rubber, the problem is avoided since the particles are too large to block the pores. This problem refers to polymers that are not water-soluble in the form of emulsified particles, whereby the same polymers that are in solution may cause blocking or clogging of the pores. However, PEDOTPSS or PEDOT-PSSH do not appear to block ion transport.

In figure 4 an even further step of methods 100 and 200 presented above, may be provided. According to method 300, comprising steps 310,

320 and 330 and 340, similar to steps 210, 220, 230 and 240 of method 200, the composition 5 may be further comprising an electrically conducting addidtive 7, by the step e of adding 350 the electrically conducting addidtive to the composition 5 comprising a binder 6. The electrically conducting addidtive 7 may be activated carbon, graphite nanofiber, carbon nanotube or poly(3,4 ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS) or sulfonic acid (PEDOT-PSSH). However, activated carbon is preferred because of its properties and that it is relatively cheap compared to the materials currently used on the market. Further, the amount of electrically conductive additive 7 in relation to porous material 1 is depending on which properties of the composition 5 which are desirable. For example, it is possible to add electroconducting CB as native material, CB, or as a CB coated with redox polybenzoxazine, i.e. HQ-PBz@CB. It is also possible to add more CB, but at the loss of charge storing capacity of the HQ-PBz@AC.

It may even be possible to add only HQ-PBz@CB and no HQ-PBz@AC. Example 4 explicitly shows an example of the preparation of a component 9 comprising a conductor 10, in this case PEDOT-PSS, which also acts as a binder, wherein the hydroquinone-polybenzoxazine (HQ-PBz) 3 cross-linked on the surface of porous particles 2 represented of carbon black (CB), is mixed with PEDOT-PSS in DMSO. Thus, the weight ratio is 66.7% HQ- PBz@AC and 33.3% PEDOT-PSS. Correspondingly, in example 5, the hydroquinone-polybenzoxazine 3 cross-linked on the surface of porous particles 2 represented of activated carbon (AC), is mixed with PEDOT-PSS in DMSO and forming an electrode composition HQ-PBz@CB. DMSO acts as a solvent, whereas PEDOT-PSS acts as a binder. DMSO also has the effect of providing the PEDOT-PSS with high conductivity. Both the materials obtained in examples 4 and 5 were achieved as pastes as illustrated in figure 7. Analysis

Example 7 describes the electrochemical characterization of the electrode components 65 based on carbon particles as described in examples 4 and 5, respectively. The electrochemical characterization was performed by cyclic voltammetry (CV) measurement and the cyclic voltammograms shown in figures 5 and 6 displayed the electrochemical activity of both hydroquinone-based polybenzoxazine 3 on activated carbon (HQ-PBz@AC) and hydroquinone-based polybenzoxazine 3 on carbon black (HQ-PBz@CB), respectively. In addition to that, CV data reveal the stability of the redox system within the different carbon particle network. First, it could be observed that the oxidation and reduction peak currents of hydroquinone (HQ) shows very little change over high number of scans (400) for both HQ- PBz@CB and HQ-PBz@AC electrode components 65. These results shows that hydroquinone moieties are stably immobilized on the carbon particles 2, one of the main objectives of the invention. The CV measurement were run for more than 15 hours in 1 M H2SO4 solution.

Applications

Due to its highly interesting redox properties, the porous material 1 and/or the composition 5 may find use in a great variety of applications, which will be described further below.

Energy storage devices

For example, in figure 11 an energy storage device 20, such as a battery 30 and/or a super capacitor 40, comprising an electrolyte 21 arranged between a pair of electrodes 22, 24, which electrodes are sandwiched between a pair of conductors 26, 28 and an electrolyte 21, wherein at least one of said electrodes 22, 24 comprises a porous material 1 according to the first aspect or a composition 5 of the second aspect, wherein an electrode having high resistivity is provided. Said conductors may be formed of metal foils, such as aluminum or copper. Batteries

A battery is a electrical power source consisting of one or more electrochemical cells with external connections for powering electrical devices such as low-power labels with flexible displays, flashlights, mobile phones and electric cars. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy products, and the free-energy difference is delivered to the external circuit as electrical energy. A battery may be referred to a device composed of both a single cell and multiple cells.

The use of the porous material 1 in battery applications yields a more stable electrode component 65 with redox functionality.

Super capacitors

A supercapacitor (SC) or an ultracapacitor, is a high-capacity capacitor with a capacitance value much higher than standard capacitors, but with lower voltage limits, that bridges the gap between electrolytic capacitors and rechargeable batteries. A SC typically stores 10 to 100 times more energy per unit volume or mass than electrolytic capacitors. The SC may accept and deliver charge much faster than batteries and tolerates many more charge and discharge cycles than rechargeable batteries. Supercapacitors are used in applications requiring many rapid charge/discharge cycles, rather than long-term compact energy storage. Further, in contrast to ordinary capacitors, SCs do not use the conventional solid dielectric, instead they use electrostatic double-layer capacitance (EDLC) and electrochemical pseudocapacitance, both of which contribute to the total capacitance of the capacitor, with a few differences. Electrostatic double-layer capacitors (EDLCs) use carbon electrodes or derivatives with much higher electrostatic double-layer capacitance than electrochemical pseudocapacitance, thus achieving a separation of charge in a Helmholtz double layer at the interface between the surface of a conductive electrode and an electrolyte. The separation of charge is of the order of a few angstroms, i.e. 0.3-0.8 nm, which is much smaller than in a conventional capacitor. On the other hand, electrochemical pseudocapacitors use metal oxide or conducting polymer electrodes with a high amount of electrochemical pseudocapacitance additional to the double-layer capacitance, wherein pseudocapacitance is achieved by Faradaic electron charge-transfer with redox reactions, intercalation or electrosorption.

A component comprising the porous material 1 with the same structure can be used for different applications or purposes. For example, there are cases where it is the use of the component, e.g. how and when it is powered by a voltage, that determines what kind of component it is. Further, figure 11 shows the device in the form of sandwiched plates. However, the device is not limited to that particular form. For example, device may also be in the form of a cylinder, wherein one electrode is a rod that is surrounded by an electrolyte which in turn is surrounded by a cylindrical electrode.

Electrochromic devices

The composition 5 may be used as an electrode component 65 or as a coating on partly or fully covering the area of an electrode component 65 in a printed circuitry, e.g. a counter electrode in a printed electrochromic display. Figure 8 illustrates how the composition 5 (or a printable or coatable ink 8) comprising the porous material 1 may be applied by a coating or printing process 400 for manufacturing of electronic circuitries 60. In method 400, a substrate 62 is provided 410 in step a. Then a circuitry 60 is provided 420, by coating a portion of said circuitry 60 with the composition 5, on said substrate 62 by means of printing 430. There are several printing techniques that may be used, figure 8 shows stencil printing. The substrate may be chosen depending on the application for the specific use, such as plastic and/or paper-based substrates e.g. PET or cardboard. Chemical biosensors

A biosensor is a device that measures biological or chemical reactions by generating signals proportional to the concentration of an analyte in the reaction. Biosensors are employed in applications such as disease monitoring, drug discovery, and detection of pollutants.

A composite of polyhydroquinone and reduced graphene oxide (PHQ- rGO) have been developed in the prior art, to function in electrodes with immobilized redox functions in biosensors. A problem with PHQ is that it is nominally an unbranched polymer that may dissolve in electrolyte media. Another drawback is the high costs of GO. A further drawback is that there is no control of the phase dimensions in the formed composite, PHQ may reside in large phases separated from rGO, which can limit charge transfer between the redox center and the conducting rGO. Thus, a problem presented in the field of biosensors may thus be how to combine a stably immobilized redox function in an electrode material for the detection of peroxide and oxygen.

An aspect of the present invention provides a solution to this problem by implementing the porous material 1 of the first aspect or composition 5 of the second aspect into a sensor 50 wherein said composition 5 may be used as a reference electrode or mediator. In such case, there is no particular need for high conductivity near the redox function. “Electrical conductivity” or “specific conductance” is the reciprocal of resistivity and measures a material's ability to conduct an electric current.

A practical limitation with present invention may be when it comes to the use within biosensors. This is because the benzoquinone-hydroquinone redox system operates best at low a pH, i.e. in the range below pH 4, whereas biosensors function at a pH close to neutral, i.e. typically pH 5.5 to 7. The present invention provides a solution to this problem by either using a polymer acid as binder, such as PEDOT-PSSH, or to provide a top coating of cross-linked polymer sulphonic acid, such as Nafion, on the porous material. Heavy metal absorption

The chelating ability of polybenzoxazines towards heavy metal ions is known in the prior art. For example, the chelating power of polybenzoxazines in aerogels to remove mercury ions from water have been described. Here, the combination of porosity with the chelating properties is the key to the efficient heavy metal sorption. In one aspect of the invention, the polybenzoxazine 3 is spread as a thin film on a large surface area substrate. In this configuration, the polybenzoxazine 3 is well suited to act as sorbent for heavy metal ions present in water. Thus, as shown if scheme 2 and figure 10, removal of heavy metal ions from water may be achieved by method 500, by contacting 510 heavy metal contaminated water with the porous material 1 of the present invention. Thus, adsorption 520 of heavy metal ions on the porous material 1 is achieved. The method 500 is advantageous since the porous material 1 has a large surface area and the porous material 1 may be tailored regarding the pore size. Further, it is environmentally sustainable since it may be regenerated by the desorption of metal ions by the addition of mineral acids, such HNO3 (aq.), H2SO4 (aq.) or HCI (aq.).

M ²⁺ (aq.) Scheme 2. Examples

Example 1

Preparation of a porous material 1, HQ-PBz@CB, comprising immobilization by polymerization of a hydroquinone-based benzoxazine 3 onto carbon black 2.

HQ-Bz monomer 4 was manufactured according to a method of Dumas et al. (Eur. Polym. J. 75 (2016) 486-494) but by replacing aniline for furfurylamine. Thus, 30 mg of HQ-Bz 4 was added to 150 mg of carbon black (CB), Imerys TIMCAL 250 G, as porous particles 2. The mixture was stirred as a solid powder while the temperature was raised to 160 °C to melt the HQ-Bz 4.

Agitation was continued for 1 hour. Thereafter, the temperature was raised to 230 °C and was kept there for 1 hour to complete the polymerization to yield the porous material 1. Example 1a

Preparation of a porous material 1, HQ-PBz@AC, comprising immobilization by polymerization of a hydroquinone-based benzoxazine 4 onto activated carbon 2.

HQ-Bz monomer 4 was manufactured according to a method of Dumas et al. but by replacing aniline for furfurylamine. Thus, 248 mg of HQ-Bz 4 was added to 497 mg of AC, Haycarb HCE 202, as porous particles 2. The mixture was stirred while the temperature was raised to 160 °C to melt the HQ-Bz 4. Agitation was continued for 20 minutes to let the monomer melt soak into the activated carbon. Thereafter, the temperature was raised to 180 °C and was kept there for 20 minutes to dry and degas the sample before polymerization at 240 °C for 30 minutes to yield the porous material 1.

Example 2

Preparation of a porous material 1, HQ-PBz@AC, comprising immobilization by polymerization of a hydroquinone-based benzoxazine 4 onto activated carbon 2. HQ-Bz monomer 4 was manufactured according to a method of Dumas et al. but by replacing aniline for furfurylamine. Thus, 248 mg of HQ-Bz 4 was added to 497 mg of AC, Haycarb HCE 202, as porous particles 2. The mixture was stirred while the temperature was raised to 160 °C to melt the HQ-Bz 4. Agitation was continued for 20 minutes to let the monomer melt soak into the activated carbon. Thereafter, the temperature was raised to 180 °C and was kept there for 20 minutes to dry and degas the sample before polymerization at 240 °C for 30 minutes to yield the porous material 1.

Example 2a

Preparation of a porous material 1, HQ-PBz@AC, comprising immobilization by polymerization of a hydroquinone-based benzoxazine 4 onto activated carbon 2.

HQ-Bz 4 was synthesized according to Yagci etal. (Eur. Polym. J. 142 (2021) 110157). After completion of the reaction, the reaction vessel was removed from the oil bath and the reaction vessel was connected to vacuum to remove volatiles. The product was dissolved in dichloromethane, 150 ml_. A precipitate formed that was removed by filtration and discarded, and the filtrate was extracted with 1 N NaOH three times and deionized water three times. The solvent was removed by rotary evaporation and the contents were dried by exposure to vacuum for three days. Activated carbon (YP-50-F from Kuraray), 2.51 g, (with a measured specific surface area of 1745 m ² /g) was placed in a 100 ml_ round bottom glass flask with a large magnetic stirring bar and the activated carbon was degassed by application of vacuum, first at ambient temperature, then 120 °C, to remove gases and absorbed volatile substances. After cooling to room temperature the above synthesized HQ-Bz, 2.51 g, was added to the activated carbon to afford a particle mixture. The particle mixture was stirred vigorously with a magnetic stirrer as the temperature was raised to 160 °C to melt HQ-Bz. As the HQ-Bz melted a slurry mixture was initially formed. As the low viscous melt was absorbed by the activated carbon, the carbon powder dried up and no free liquid phase between the particles could be observed. The temperature was kept at 160 °C for one hour. After this, the temperature was raised in steps to 240 °C during three hours, and was kept at 240 °C for two hours to complete the polymerization. Stirring was maintained during the course of the reaction. The product had the appearance of the starting material, a dry powder of activated carbon. The specific surface area was analyzed and found to be 5.1 m ² /g.

Example 3

One-pot preparation of a porous material 1 (without solvent), HQ-PBz@AC.

HQ-Bz 4 was manufactured following the reaction scheme described by Dumas et al. , but without performing the purification steps after the reaction. Instead, the crude monomer remained in the reaction vessel, carbon particles were added and the temperature was gradually raised to afford the product in a one-pot process. First, 31 mg hydroquinone in 55 mg furfurylamine at 120 °C under agitation with a magnetic stirrer on a hot-plate in a glass vial with flat bottom. Then 38 mg para-formaldehyde was added. After 25 minutes the temperature was raised to 140 °C and the mixture was degassed before 200 mg of AC, Norit A Supra was added to the reaction vessel. The temperature was raised to 160 °C to melt the HQ-Bz. The mixture was agitated until all fluid monomer was soaked into the particles to provide apparently dry particles. After 20 minutes, the particles were further degassed before the temperature was raised to 180 °C. After 20 minutes, the temperature was raised to 240 °C to polymerize the HQ-Bz 4, still under agitation. Agitation was continued for 20 minutes. Cooling provided the porous material 1 in a one-pot process.

Example 3a

Impregnation assisted by vacuum and solvent of HQ-Bz monomer into porous activated carbon.

HQ-Bz 4 was synthesized according to Yagci et al. After completion of the reaction, the reaction vessel was removed from the oil bath and the reaction vessel was connected to vacuum to remove volatiles. The product was dissolved in dichloromethane, 150 ml_. A precipitate formed that was removed by filtration, and the filtrate was extracted with 1 N NaOH three times and deionized water three times. The solvent was removed by rotary evaporation and the contents were dried by exposure to vacuum for three days. Activated carbon (YP-50-F from Kuraray, with a measured specific surface area of 1745 m ² /g), 2.5 g, was degassed by application of vacuum, first at ambient temperature, then 120 °C, to remove gases and absorbed volatile substances. After cooling to room temperature the above synthesized HQ-Bz, 1.25 g, dissolved in 5 ml_ dichloromethane was injected through a septum into the vessel holding the activated carbon under vacuum. The slurry with activated carbon was stirred vigorously with a magnetic stirrer for one hour before the solvent was removed by application of vacuum. At this stage, the activated carbon appeared dry and no wet phase was observed, indicating that most material reside inside the carbon particles. The vacuum was maintained for two days at room temperature before the temperature was raised to and kept at 50 °C for one hour and then to 75 °C for one hour, to remove volatiles before the temperature was raised gradually to polymerize the monomer. The temperature was ramped up to 170 °C, where it was kept for one hour, then kept at 200 °C for one hour and finally 230 °C for one hour, while maintaining vigorous stirring during the hearing process. The specific surface area was analyzed and found to be 94.9 m ² /g.

Example 3b

Impregnation assisted by vacuum and solvent of HQ-Bz monomer into porous granular activated carbon.

The procedure in example 3a was followed except that the instead of the activated carbon powder, granulated activated carbon (Aquasorb 20008x30 mesh, Jacobi) was used, and that the mixture was agitated mildly and only shortly with intervals to avoid grinding and wear of the granules. Example 3c

Copolymerization of HQ-Bz monomer with 1,2-dihydroxyanthraquinone (alizarin)

Carbon black (TIMCAL G, 2.52 g) was placed in a round bottom flask with a magnetic stirrer and connected to vacuum. After heating to 100 °C, the flask was cooled to ambient temperature and a mixture of alizarin (Az) (Fisher, art no. 10796161, 12.5 mg) and HQ-Bz (Acros, art. no. 153691000, 248 mg) dissolved in 25 mL acetone was transferred into the flask with carbon black by the vacuum. Acetone was removed by application of reduced pressure at ambient temperature. After drying at ambient temperature, the dry impregnated powder was kept at 100 °C for 60 min, before being raised to and kept at, 140 °C, 30 min, 180 °C, 60 min, 200 °C, 30 min, 230 °C, 45 min. The product HQ-PBzAz@CB was used to form coating and printing compositions.

Example 3d

Copolymerization of HQ-Bz monomer with 3,4-dihydroxy-9,10-dioxo-2- anthracenesulfonic acid sodium salt (alizarin S red)

Carbon black (TIMCAL G, 2.51 g) was placed in a round bottom flask with a magnetic stirrer and connected to vacuum. After heating to 100 °C, the flask was cooled to ambient temperature and alizarin S red (Merck, art. No.,

A5533, 45 mg) dissolved in 25 mL ethanol was sucked into the flask with carbon black by the vacuum. The solvent was removed by vacuum at ambient temperature before 198 mg HQ-Bz dissolved in 10 mL acetone was transferred by vacuum into the flask. The solvent evaporation procedure was repeated, and the temperature was ramped up in steps and kept at 50 °C for 90 min, at 130 °C for 45 min, 180 °C 45 min and at 230 °C for 60 min to produce the HQ-PBz incorporated on alizarin S red while loaded at carbon black. Example 4

An electrode composition 5 from HQ-PBz@CB 1 and PEDOT-PSS.

HQ-PBz@CB and PEDOT-PSS-5% in DMSO were mixed in a 1:10 mass ratio to produce a paste of composition 5 for electrode coating. The dry matter ratio of the binder is 5% dry weight in the the DMSO solution.

Example 5

An electrode composition 5 from HQ-PBz@AC 1 and PEDOT-PSS.

HQ-PBz@AC from Example 1a and PEDOT-PSS-5% in DMSO were mixed in a 1 :5 mass ratio to produce a paste of composition 5 for electrode coating.

Example 5a

An electrode composition 5 from HQ-PBz@CB 1 and PEDOT-PSSH.

Electrode composition with an acidic and conducting binder matrix specifying the matrix to be PEDOT:PSSH where the PSSH is in the free acid form.

Example 5b

An electrode composition 5 from HQ-PBz@AC 1 and PEDOT-PSSH.

Electrode composition with an acidic and conducting binder matrix specifying the matrix to be PEDOT:PSSH where the PSSH is in the free acid form.

Example 6

An electrode composition 5 from HQ-PBz@CB 1 and P(VDF-TrFE) 6.

HQ-PBz@CB, and P(VDF-TrFE), i.e. Poly(vinylidene fluoride-co- trifluoroethylene), 70:30 x 5 % in a mixture of Acetone and DBE-9 (1:1) were mixed in a 0.23:1 mass ratio to produce a paste for electrode coating.

Example 1

Electrochemical characterization of electrode components 65 based on carbon particles

Pastes of porous material 1, HQ-PBz@CB and HQ-PBz@AC prepared as described in examples 4 and 5, respectively, were coated on carbon electrodes, printed on top of aluminum current collectors and dried by heating 100 °C for 60 sec. Electrochemical measurements (cyclic voltammetry and charge / discharge cycling, were performed by three electrode setups with platinum counter electrode and Ag/AgCI reference electrode in 1 M H2SO4.

Example 8

Electrodes coated with an acidic membrane for use in e.g. biosensors

Electrodes manufactured according to example 4a and 5a wherein 2 microliters of a Nafion solution obtained by diluting 5% Nafion solution from Merck, product no. 70160, with 1.5 parts ethanol, was drop cast on the electrode and dried at room temperature.

Impurities that result from the synthesis of benzoxazine are typically removed e.g. by a separation and purification process comprising removing the monomers from the reaction vessel for e.g. filtration, extraction and drying. However, the impurities appear to not disturb the polymerization of benzoxazine. In some cases, the presence of impurities can be tolerated. It is therefore possible to obtain a desired product using a one-pot process, i.e. without removing the monomers from the reaction vessel, if e.g. low cost is a priority, since it is much simpler and cheaper. For the one-pot process, however, a low melt viscosity of the monomer is normally needed, which limits the choice of ratio of benzoxazine to activated carbon. It can also lead to uneven distribution of monomers in different particles. Consequently, in the examples above, when HQ-Bz monomer 4 is manufactured according to a method of Dumas et al. , the process is not a one-pot process in the way the term is used in relation to this invention. ITEMIZED LIST OF EMBODIMENTS A porous material (1 ) comprising porous particles (2) coated with a cross-linked polybenzoxazine (3) having free phenol groups, wherein the polybenzoxazine (3) is a polymer product of a monomer (4) selected from the group consisting of formula I, formula II, and formula III: wherein R ¹ is selected from (Ci-Ci6)alkyl, (Ci-Cio)alkenyl, (Ci- Cio)alkynyl, (C3-C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-Ci6)alkyl and heteroaryl(Ci-Ci6)alkyl, each substituted with one or more R ² , or unsubstituted; and R ² is selected from hydroxy, halogen, cyano, nitro, amino, (Ci-C3)alkyl, (Ci-C3)alkenyl, (Ci-C3)alkynyl, (C3-C6)cycloalkyl, phenyl, heteroaryl, (Ci-C3)acyl, (Ci-C3)alkoxy.

The porous material (1) according to item 1, wherein the polybenzoxazine (3) is a polymer product of a monomer (4) of formula I or formula II. The porous material (1) according to item 1 or 2, wherein the polybenzoxazine (3) is a polymer product of a monomer (4) of formula

4. The porous material (1) according to any one of items 1 to 3, wherein R ¹ is selected from (Ci-Ci2)alkyl, (Ci-C-io)alkenyl, (Ci-C-io)alkynyl, (C3- C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-C3)alkyl and heteroaryl(Ci-C3)alkyl.

5. The porous material (1) according to any one of items 1 to 4, wherein R ¹ is selected from the group consisting of phenyl, furfuryl and (Ci- Ci2)alkyl, such as phenyl or furfuryl.

6. The porous material (1) according to any one of items 1 to 5, wherein the porous particles (2) have a specific surface area in the range of 1 - 2600 m ² /g, preferably 5 - 2500 m ² /g, preferably 25 - 2000 m ² /g.

7. The porous material (1) according to any one of items 1 to 6, wherein the porous particles (2) are selected from activated carbon, carbon black, graphite nanofiber, carbon nanotube, and silica. 8. The porous material (1) according to any one of items 1 to 7, wherein the porous particles (2) are activated carbon or carbon black.

9. A composition (5) for coating and/or printing, comprising: a porous material (1) according to any one of items 1 to 8; and a binder (6). The composition (5) according to item 9, wherein the binder (6) is selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride copolymers, poly(3,4-ethylenedioxy-thiophene)- polystyrene sulfonate, butadiene rubber, and polysaccharide binders including nano- or m i crof i brill ated cellulose, carboxymethylated derivates, cellulose derivatives, or alginates. The composition (5) according to item 9 or 10, further comprising an electrically conducting additive (7) selected from carbon black, graphite nanofiber, carbon nanotube and poly(3,4-ethylenedioxythiophene)- polystyrene sulfonate, such as carbon black. A composition (5) for coating and/or printing, comprising: a porous material (1 ) according to any one of items 1 to 8; a solvent; and a binder (6). The composition (5) according to item 12, wherein the solvent is selected from the group consisting of dimethyl glutarate, dimethyl adipate, dimethyl succinate, DBE-3, DBE-9, dipropylene glycol diacetate and dimethyl sulfoxide, or mixtures thereof; and the binder (6) is selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride copolymers, butadiene rubber, and polysaccharide binders including nano- or microfibrillated cellulose, carboxymethylated derivates, cellulose derivatives, or alginates, preferably the solvent is DBE-9 and the binder is polyvinylidene fluoride. A printable or coatable ink (8) comprising a composition (5) according to any one of items 9 to 13. 15. A method of producing a conductor comprising the steps of: providing a carrier, and depositing a composition (5) according to item 11 on said carrier. 16. A component (9) comprising a conductor (10) coated with a porous material (1) according to any one of items 1 to 8, and further comprising an electrically conducting additive (7) selected from carbon black, graphite nanofiber, carbon nanotube and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, such as carbon black.

17. The component (9) according to item 16, wherein the component (9) is an electrode component (65) or an electrochemical cell (70), such as an energy storage device (20), a battery (30), a super capacitor (40), a sensor (50), a printed electrochromic cell (80), or a transistor (90), or combinations thereof.

18. A method (100) for producing a porous material (1 ) by coating porous particles (2) with a cross-linked hydroquinone-based polybenzoxazine

(3) having free phenol groups, comprising the steps of: a. providing (110) a mixture of porous particles (2) and a benzoxazine monomer (4) selected from the group consisting of formula I, formula II, and formula III: III wherein R ¹ is selected from (Ci-Ci6)alkyl, (Ci-C-io)alkenyl, (Ci- Cio)alkynyl, (C3-C6)cycloalkyl, 3 to 6-membered heterocycloalkyl, aryl, heteroaryl, aryl(Ci-Ci6)alkyl and heteroaryl(Ci-Ci6)alkyl; b. heating (120) the mixture of porous particles (2) and the benzoxazine monomer (4) at a temperature above a melting point of the benzoxazine monomer (4) and below an onset temperature of thermal polymerization of the benzoxazine monomer (4 under agitation; and c. raising (130) the temperature above the onset temperature of thermal polymerization of the benzoxazine monomer (4), thereby forming the porous material (1) by thermal ring-opening, curing and cross-linking of the benzoxazine monomer (4) under agitation.

The method according to item 18, wherein the benzoxazine monomer

(4) is of formula I or formula II.

The method according to item 18 or 19, wherein the benzoxazine monomer (4) is of formula I: 21. The method (100) according any one of items 18 to 20, wherein the benzoxazine monomer (4) selected from the group consisting of formula I, formula II, and formula III is produced by reacting paraformaldehyde, R ¹ NH2 and hydroquinone for forming the monomer (4) of formula I; 2,6-dihydroxyanthraquinone for forming the monomer

(4) of formula II; and 2,7-dihydroxyanthraquinone for forming the monomer (4) of formula III.

22. The method (100) according to any one of items 18 to 21 , wherein the method (100) is a one-pot process.

23. The method (100) according to any one of items 18 to 22, wherein steps a, b, and c are performed without the addition of any solvent. 24. The method (100) according to any one of items 18 to 23, wherein the melting point of the benzoxazine monomer (4) is lower than the polymerization onset temperature by at least 10 °C.

25. The method (100) according to any one of items 18 to 24, wherein the melting point of the benzoxazine monomer (4) is between a range from

20 to 180 °C, such as 60 to 160 °C.

26. The method (100) according to any one of items 18 to 25, wherein the onset temperature of thermal polymerization of the benzoxazine monomer (4) is between a range from 150 to 300 °C, such as 170 to

300 °C, or 200 to 300 °C.

27. A method (100, 200) for producing a composition (5) for coating and/or printing, comprising the method according to any one of items 18 to 26, further comprising the step of: d. mixing (240) said porous material (1) with a binder (6) dissolved in a water-based or an organic solvent. 28. The method (100, 200, 300) according to item 27, further comprising the step of: e. adding (350) an electrically conducting additive (7) to the resulting composition (5) of step d or to the porous material (1 ) resulting from step c.

29. Use of the composition (5) according to any one of items 9 to 11 or a component (9) according to item 13 in a sensor (50).

30. Use of the composition (5) according to any one of items 9 to 11 or a component (9) according to item 16 in an electrode component (65) or an electrochemical cell (70), such as an energy storage device (20), a battery (30), a super capacitor (40), a printed electrochromic cell (80), or a transistor (90). 31. A method (400) of manufacturing an electronic circuitry (60) comprising the steps of: a. providing (410) a substrate (62); b. providing (420) a circuitry (60) on said substrate (62) by means of printing (430), wherein said step of providing (420) said circuitry comprises coating a portion of said circuitry (60) with the composition (5) according to any one of items 9 to 11.

32. A method (500) for removal of heavy metal ions from heavy metal contaminated water, comprising the steps of: a. contacting (510) heavy metal contaminated water with a porous material (1) according to items 1 to 8; b. adsorbing heavy metal ions on said porous material (1).

33. Use of a porous material (1 ) according to items 1 to 8 for removal of heavy metal ions from heavy metal contaminated water.