CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit of US Provisional Application No. 63/327,148 filed on April 4, 2022. US Provisional Application No. 63/327,148 is incorporated herein by reference. A claim of priority is made.

BACKGROUND

[0002] Degradable polymers are recently emerging as promising materials due to the environmental concern of non-degradable polymer materials. Degradable polymers may be utilized for applications in transient devices, lithography, and as stimuli responsive materials. Aldehydes, composing of a highly polar carbon-oxygen double bond, can undergo ionic polymerization to form polyaldehydes or polyacetals. Due to the instability of the ketal linkage in the backbone, polyaldehydes are emerging as smart and stimuli-responsive materials for applications such as drug delivery and nanomanufacturing. However, due to the small enthalpy change from the carbon-oxygen double bond to a single bond after polymerization, the ceiling polymerization temperatures (T _c ) of most aldehydes are generally below room temperature. Accordingly, the longer the length of the aldehyde, the lower the ceiling polymerization temperature. Endcapping the labile hemiacetal chain ends is necessary to prevent depolymerization of polyaldehydes under ambient conditions or elevated temperatures. Therefore, it would be beneficial to produce degradable polymers at mild temperatures and pressures that exhibit good thermal stability and processibility.

SUMMARY

[0003] According to one aspect, a degradable copolymer includes polyethers, polyesters, and polycarbonates. This degradable copolymer may be formed from o-phthalaldehyde (oPA) and one or more monomers.

[0004] According to another aspect, a method of forming a degradable polymer includes contacting o-phthalaldehyde (oPA) with a first monomer in the presence of an activator and an organic Lewis base or an initiator, wherein the first monomer includes a monomer selected from a cyclic epoxide, a cyclic episulfide, a cyclic aziridine, and a cyclic ester. [0005] According to another aspect, a method of forming a degradable copolymer includes contacting o-phthalaldehyde (oPA) with a first monomer in the presence of an activator, initiator, and a base, wherein the first monomer includes two or more hydroxyl groups, and wherein contacting includes forming a multi-anion from the first monomer and the initiator, sufficient to form the degradable copolymer in more than one direction.

BRIEF DESCRIPTION OF DRAWINGS

[0006] This written disclosure describes illustrative embodiments that are non-limiting and non-exhaustive. Reference is made to illustrative embodiments that are depicted in the figures, in which:

[0007] FIG. 1 illustrates a method 100 of forming a copolymer, according to some embodiments.

[0008] FIG. 2 illustrates a method 200 of forming a copolymer, according to some embodiments.

[0009] FIG. 3 illustrates a method 300 of forming a copolymer, according to some embodiments.

[0010] FIG. 4 illustrates a 400 MHz ¹ H NMR spectrum for alternating copolymer P(PO- aZt-oPA) (Table 1, Entry 3), according to some embodiments.

[0011] FIG. 5 illustrates GPC traces of alternating copolymer P(PO-aZt-oPA) (Table 1, Entry 3) and its degradation after thermal and acid treatment, according to some embodiments. [0012] FIG. 6 illustrates a 400 MHz ¹ H NMR spectrum for random copolymer P(PO-co- oPA) (Table 1, Entry 12), according to some embodiments.

[0013] FIG. 7 illustrates GPC curves for TBAS initiated random copolymer P(PO-co- oPA) (Table 1, Entry 12), prepared by sequential polymerization method (iterative method), according to some embodiments.

[0014] FIG. 8 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 12, after acid degradation and TFAA modification in CDCh, according to some embodiments.

[0015] FIG. 9 illustrates a 400 MHz ¹⁹ F NMR spectrum for Table 1, Entry 12, after acid degradation and TFAA modification in CDCh, according to some embodiments.

[0016] FIG. 10 illustrates a 400 MHz ¹ H NMR spectrum for Table 1, Entry 13 in CDCh random copolymer of P(PC-co-oPA), according to some embodiments. [0017] FIG. 11 GPC curves for TB AS initiated random copolymer P(PC-co-oPA) (Table 1, Entry 13) using 1 bar CO2 pressure, according to some embodiments.

[0018] FIG. 12 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 15 in CDCh random copolymer of P(PO-co-oPA-PA) (unreacted monomer oPA* and PO ^# ), according to some embodiments.

[0019] FIG. 13 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 5 in CDCh random copolymer of P(EO-co-oPA), according to some embodiments.

[0020] FIG. 14 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 6 in CDCh alternating copolymer of P(BO-aZt-oPA), according to some embodiments.

[0021] FIG. 15 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 7 in CDCh alternating copolymer of P(OO-aZt-oPA), according to some embodiments.

[0022] FIG. 16 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 8 in CDCh random copolymer of P( AGE-co-oP A), according to some embodiments.

[0023] FIG. 17 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 9 in CDCh alternating copolymer of P(PGE-aZt-oPA), according to some embodiments.

[0024] FIG. 18 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 10 in CDCh random copolymer of P(SO-co-oPA), according to some embodiments.

DETAILED DESCRIPTION

[0025] Typically, the copolymerization of ortho-phthalaldehyde (oPA) must occur at temperatures below the ceiling temperature (T _c ~ -40 °C). Embodiments of the present disclosure describe a novel method for forming degradable copolymers, such as poly acetals and polycarbonates, using oPA and one or more of monomers, organocatalysts/activators, bases, and initiators. Further, these methods of forming copolymers may occur under ambient conditions at room temperature or at elevated temperatures. oPA may be copolymerized with a wide range of monomers to produce ketal-containing poly ethers, polyesters, and polycarbonates. High molar mass polyether, polyester, and polycarbonate polyols may be randomly incorporated by oPA using multifunctional initiator/chain transfer. Further, these copolymers may be treated to cleave the copolymer and decrease the molar mass. Additionally, the carbonate content may be tuned under different polymerization pressures and treatment methods. [0026] Copolymerization and terpolymerization of oPA sufficient to form a degradable copolymer may include one or more of monomers, organocatalysts/activators (such as a Lewis acid), bases, and initiators. These degradable copolymers may include degradable linkages, such as a portion/segment of the polymer capable of being degraded. For example, a degradable linkage may include an acetal linkage. Copolymerization may include forming the polymer from two or more distinct monomers. Terpolymerization may include forming the polymer from three or more distinct monomers. Copolymerization and terpolymerization may be used interchangeably in the present disclosure to describe reacting oPA with one or more distinct monomers. In one example, the monomers may include one or more of cyclic monomers and carbon dioxide. For example, cyclic monomers may include cyclic epoxides, cyclic episulfides, cyclic aziridines, and cyclic esters. One example of a suitable monomer is shown below, where Z may be oxygen, nitrogen, or sulfur. In one example, Ri and R2 may be selected from an alkyl group and an aryl group.

[0027] An alkyl group may refer to saturated, straight- or branched-chain hydrocarbon radicals in which a hydrogen atom has been removed from an aliphatic moiety. An alkyl group can optionally include a straight or branched chain with 1 to 20 carbons. Non-limiting examples of alkyls include a methyl group, ethyl group, n- propyl group, iso-propyl group, n-butyl group, iso-butyl group, and the like. An aryl group may refer to a monocyclic or polycyclic ring system having from 5 to 20 carbon atoms, wherein at least one ring in the system is aromatic and wherein each ring in the system contains three to twelve ring members. Non-limiting examples of aryls include a phenyl group, methylphenyl, (dimethyl)phenyl, ethylphenyl, biphenyl group, indenyl group, anthracyl group, naphthyl group, or azulenyl group, and the like.

[0028] Examples of monomers utilized for copolymerization and terpolymerization include oxiranes/epoxides. In one example, oxiranes include ethylene oxide, propylene oxide, 1 -butene oxide, octene oxide, allyl glycidyl ether, phenyl glycidyl ether, and styrene oxide. In another example, monomers may be selected from the oxiranes listed below. R3 and R4 may be selected from an alkyl group and an aryl group.

[0029] Examples of monomers utilized for copolymerization and terpolymerization include dioxiranes. In one example, dioxirane monomers may be selected from the dioxiranes below.

[0030] Examples of monomers utilized for copolymerization and terpolymerization include cyclic esters. Cyclic esters may refer to monoesters, cyclic diesters, cyclic triesters, and the like. In one example, cyclic esters may include Lactide, such as L-lactide, D-lactide, and meso-lactide. In another example, monomers may be selected from the cyclic esters below. (Lactide, a-caprolactone, 5- valerolactone, 5-hexanolcatone, P-propiolactone, P-butyrolactone) [0031] Copolymerization and terpolymerization may include multifunctional initiators, such as utilizing di-anions, tri-anions, and multi-anions in the polymerization process. The dianions, tri-anions, and multi-anions are sufficient for polymer growth in multiple directions. For example, a diol may be transformed to a di-anion for forming a polymer in two different directions. The diol may be utilized in the presence of a base sufficient to form the polymer.

[0032] Methods may also include terpolymerization with cyclic anhydride monomers and heteroallene monomers. For example, terpolymerization may include utilizing oPA, cyclic anhydrides, carbon dioxide, and one or more of cyclic oxiranes, cyclic episulfides, and cyclic aziridine monomers. In one example, the cyclic anhydride includes phthalic anhydride. In another example, the cyclic anhydride is selected from the cyclic anhydrides below. (SA = succinic anhydride, MA = maleic anhydride, DMMA = dimethylmaleic anhydride, GA = glutaric anhydride, DGA = diglycolic anhydride, and PA = phthalic anhydride)

[0033] In one example, organocatalysts/activators or Lewis acids may include one or more alkyl boranes such as trialkyl borane (TAB). In another example, activators may include one or more of triethylborane (TEB), trialkylaluminum (TAA), and dialkyl zinc. In yet another example, the activator may be selected from an aromatic boron, alkyl aluminum, and an aromatic aluminum. The activator may have multiple functions during the polymerization process. The activator may interact with the growing chain and may activate the monomer. For example, the activator may contact an anion during polymerization sufficient to form an ate complex. The activator may activate the monomer, such as an epoxide, and block copolymerization. In one example, the initiator is selected from benzyl alcohol, tetrabutyl ammonium chloride (TBA-C1), and tetrabutyl ammonium succinate (TBAS), tetrabutyl phosphonium chloride (TBP-C1), tetraphenyl phosphonium chloride (TPP-C1), bis(triphenylphosphine)iminium chloride (PPN-C1), tetrabutyl phosphonium succinate (TBPS), and tetraphenyl phosphonium succinate (TPPS). [0034] Copolymerization and terpolymerization may include one or more bases. In one example, bases include a phosphazene base. In another example, organic Lewis bases for copolymerization and terpolymerization are selected from the bases shown below. R may be selected from an alkyl group and an aryl group.

[0035] The molar ratio for copolymerization may be expressed as the ratio of monomer/oPA/initiator/activator. The ratio of monomer/oPA/initiator/activator may be tuned sufficient for copolymerization of oPA. For example, the molar ratio may include the following ranges: monomer 50-2000; oPA 1-500; initiator 1; and activator 1-4. In one example, the molar ratio for copolymerization is 100/100/1/2. In another example, the molar ratio for copolymerization is 100/100/1/1. In yet another example, the molar ratio for copolymerization is 1000/20/1/2.

[0036] In one example, copolymerization may include utilizing a binary system to copolymerize oPA. For example, a binary system may include a (separated) anion and an activator. The anion may be an alkoxy anion, formed from the monomer and the initiator, and the activator may be selected from the activators of the present disclosure, such as an alkyl borane. Alkoxy may refer to the group -OR, where R is an alkyl and/or heteroalkyl. Nonlimiting examples of alkoxy groups include a methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, and iso-butoxy group. For example, the monomer may include two or more hydroxyl groups. In one example, copolymerization may include utilizing a bifunctional system to copolymerize oPA. For example, the same molecule may contain an activator and an anion. The anion may be an alkoxy anion, halide anion, or carboxylate anion and the activator may be selected from the activators of the present disclosure, such as an alkyl borane. In another example, the binary system may be more active for the polymerization process. In yet another example, the bifunctional system may be more active for the polymerization process.

[0037] Typically, the oPA monomer must be copolymerized at a temperature below the ceiling temperature (T _c ) of about -40 °C. In one example, normally, polymerization is not thermodynamically stable at temperatures above the ceiling temperature. In another example, ceiling temperature is (normally) the highest temperature for conversion of a monomer. Importantly, copolymerization and terpolymerization of oPA in the present disclosure may be completed at temperatures above the T _c of -40 °C. In one example, polymerization is completed at a temperature above about 15 °C and/or above room temperature (20 °C). In another example, polymerization is completed at a temperature ranging from about 15 °C to about 100 °C. For example, the polymerization may be completed at a temperature above 15 °C, above 16 °C, above 17 °C, above 18 °C, above 19 °C, above 20 °C, above 21 °C, above 22 °C, above 23 °C, above 24 °C, above 25 °C, above 26 °C, above 27 °C, above 28 °C, above 29 °C, or above 30 °C, or any value therebetween. In yet another example, polymerization is completed at a temperature ranging from 20 °C to 60 °C. In yet another example, polymerization is completed at a temperature ranging from 25 °C to 45 °C.

[0038] Advantageously, the polymerization process does not require a cooling process. Higher temperatures may increase the speed of the polymerization. Further, higher temperatures, such as temperatures at or above 15 °C, may assist a monomer in reacting more efficiently. The polymerization process may include any pressure sufficient to form polymers. For example, the polymerization process may be completed at about ambient pressure or higher than ambient pressures. In one example, the polymerization process is completed at a pressure between about 0.95 bar and about 1.1 bar. In another example, the polymerization process is completed at a pressure of about 1 bar.

[0039] The reaction time may be adjusted sufficient for copolymerization of oPA and/or may be adjusted according to the monomers utilized. In one example, the reaction time for polymerization ranges from about 1 hour to about 48 hours. In another example, the reaction time for polymerization ranges from about 5 hours to about 24 hours. In yet another example, the reaction time for polymerization ranges from about 8 hours to about 14 hours. The polymerization of oPA may be sufficient for an oPA conversion over 80%. For example, the polymerization of oPA may be sufficient for an oPA conversion over 90%, over 95%, and over 98%. The polymerization of oPA may be sufficient for an oPA conversion of 99% conversion. [0040] Polydispersity index may be a measure of the molecular weight distribution. In one example, the polydispersity index of the formed copolymer ranges from about 1 to about 4. In another example, the polydispersity index of the formed copolymer ranges from about 1 to about 2.5. In yet another example, the polydispersity index ranges from about 1 to about 1.3. For example, the polydispersity index of the formed copolymer may be about 1.01, 1.02, 1.03, 1.04, or 1.05. The polydispersity index of the formed copolymer may be less than about 1.4, less than about 1.3, less than about 1.2, or less than about 1.1. The number average molecular weight Mn(xlO ³ ) of the formed copolymer may range from about 1 to about 200. In one example, the number average molecular weight Mn(xl0 ³ ) of the formed copolymer ranges from about 2 to about 60. In another example, the number average molecular weight Mn(xl0 ³ ) of the formed copolymer ranges from 8 to 20.

[0041] The degradable copolymer may include the following structure: wherein Q is a repeating unit selected from one of the following: wherein J is selected from one of the following: and wherein Ri, R2, and R3 are selected from alkyl and aryl groups, Z is selected from oxygen, nitrogen, and sulfur, and m, n, and p are 1 or greater. For example, m, n, and p may range from 1-1000. In one example, cyclic esters may be terpolymerized with oPA and a three-membered epoxide, sulfide, or aziridine. The cyclic ester linkage may be present in “J” for the structure above.

[0042] Various forms of degradable copolymers may be formed. The formed degradable copolymer may include the following structure: wherein Ri, R2 and R3 are selected from alkyl and aryl groups, Z is selected from oxygen, nitrogen, and sulfur, and m and n are 1 or greater. For example, m may range from 1-1000 and n may range from 1-1000. This degradable copolymer may be the product of copolymerizing oPA with cyclic epoxide, cyclic episulfide, or a cyclic aziridine monomer. This degradable copolymer may be the product of copolymerizing oPA with a monomer in the presence of an alkyl borane. Further, this degradable copolymer may be the product of copolymerizing oPA at a temperature at or above 15 °C.

[0043] A reaction scheme (hereinafter referred to as Reaction Scheme 1) for the copolymerization of oPA with cyclic epoxides, episulfides, and aziridine monomers is shown below. In the reaction, R, Ri, R2, and R3 may represent alkyl and aryl groups. X may represent OH, COOH, halide, multiple-carboxylic acids, and alcohols. Examples of halides include fluorine, chlorine, bromine, and iodine. LA may represent a Lewis acid, trialkyl borane, trialkyl aluminum, and dialkyl zinc. Z may represent oxygen, nitrogen, or sulfur. In one example, m and n represent a number greater than or equal to 1.

[0044] Various forms of degradable copolymers may be formed. The formed degradable copolymer may include the following structure: wherein R3 is selected from an alkyl group and aryl group, and m and n are 1 or greater. For example, m may range from 1-1000 and n may range from 1-1000. This degradable copolymer may be the product of copolymerizing oPA with a cyclic ester. This degradable copolymer may be the product of copolymerizing oPA with a monomer in the presence of an alkyl borane. Further, this degradable copolymer may be the product of copolymerizing oPA at a temperature at or above 15 °C.

[0045] A reaction scheme (hereinafter referred to as Reaction Scheme 2) for the copolymerization of oPA with cyclic esters is shown below. In the reaction, R and R3 may represent alkyl and aryl groups. X may represent OH, COOH, halide, multiple-carboxylic acids, and alcohols. LA may represent trialkyl borane, trialkyl aluminum, and dialkyl zinc. In one example, m and n represent a number greater than or equal to 1. (R)

R-X

[0046] Various forms of degradable copolymers may be formed. The formed degradable copolymer may include the following structure: wherein Ri, R ₂ and R3 are selected from an alkyl group and an aryl group. Z may represent oxygen, nitrogen, or sulfur. M, n, and p may be 1 or greater. For example, m may range from 1-1000, n may range from 1-1000, and p may range from 1-1000. This degradable copolymer may be the terpolymerization product of polymerizing oPA with cyclic anhydrides. This degradable copolymer may be the terpolymerization product of polymerizing oPA with two or more monomers in the presence of an alkyl borane. Further, this degradable copolymer may be the product of polymerizing oPA at a temperature at or above 15 °C.

[0047] A reaction scheme (hereinafter referred to as Reaction Scheme 3) for the terpolymerization of oPA and cyclic anhydrides with cyclic oxiranes, episulfides, an aziridine monomers is shown below. In the reaction, R, Ri, R ₂ , and R3 may represent alkyl and aryl groups. X may represent OH, COOH, halide, multiple-carboxylic acids, and alcohols. LA may represent trialkyl borane, trialkyl aluminum, and dialkyl zinc. Z may represent oxygen, nitrogen, or sulfur. In one example, m, n, and p represent a number greater than or equal to 1.

[0048] A reaction scheme (hereinafter referred to as Reaction Scheme 4) for the terpolymerization of oPA and CO ₂ with cyclic oxiranes, episulfides, and aziridine monomers is shown below. In the reaction, R, Ri, R ₂ , and R3 may represent alkyl and aryl groups. X may represent OH, COOH, halide, multiple-carboxylic acids, and alcohols. LA may represent trialkyl borane, trialkyl aluminum, and dialkyl zinc. Z may represent oxygen, nitrogen, or sulfur. In one example, m, n, and p represent a number greater than or equal to 1.

[0049] oPA may copolymerize with a wide range of monomers to produce ketal- containing polyethers, polyesters, polyacetals, and polycarbonates. High molar mass polyether polyester and polycarbonate polyols may be randomly incorporated by oPA using multifunctional initiator/chain transfer. These high molar mass polyols may be cleaved into low molar mass polyols by acid and/or thermal treatment. Further, polyacetals may be stable and may be cleaved with acids, such as hydrochloric acid. In one example, acid treatment includes cleaving the formed copolymer with an acid to tune the carbonate content. In another example, acid treatment includes cleaving a polyacetal to a dialdehyde (which may have been utilized to form the poly ace tai).

[0050] In one example, thermal treatment includes heating the copolymer at/to a temperature above room temperature. In another example, thermal treatment includes heating the copolymer at/to a temperature ranging from 50 °C to 200 °C. In yet another example, thermal treatment includes heating the copolymer at/to a temperature ranging from 100 °C to 150 °C. For example, the copolymer may be heated for 1 or more hours. In one example, the copolymer is heated for about 1 hour to about 10 hours. The carbonate content of the polyols may be varied from 0 % to 100 % under different CO2 polymerization pressures. For example, the final carbonate content may be 50 % or less. In another example, the final carbonate content may be 20 % or less. The final carbonate content may be 15 % or less, 10 % or less, or 5 % or less. In one example, the CO2 polymerization pressure ranges from about 1 bar to about 15 bar. In another example, the CO2 polymerization pressure ranges from about 1 bar to about 3 bar. In yet another example, the CO2 polymerization pressure is about 1 bar.

[0051] The degradable polymers of the present disclosure are formed with a wide range of monomers and activators. These degradable polymers may be utilized for packing, binder applications, coatings, drug delivery, and lithography. The degradable polymers may be high molar mass polymers. Further, these degradable polymers may be random copolymers or alternating copolymers. For example, an alternating P(PO-aZt-oPA) copolymer may be formed and optionally degraded after formation. The P(PO-aZt-oPA) copolymer may be formed from propylene oxide and oPA, using TEB and TBA-C1. In another example, a random P(AGE-co- oPA) copolymer may be formed and optionally degraded after formation. The P(AGE-co-oPA) copolymer may be formed from allyl glycidyl ether and oPA, using TEB and TBA-C1.

[0052] Importantly, due to the small enthalpy change from a carbon-oxygen double bond to a single bond after polymerization, the ceiling polymerization temperatures (T _c ) of most aldehydes are generally below room temperature. The longer the length of the aldehyde, the lower the ceiling polymerization temperature. Endcapping the labile hemiacetal chain ends was conventionally necessary to prevent depolymerization of polyaldehydes under ambient conditions or elevated temperature. Alternatively, oPA could be polymerized below its T _c temperature. In contrast, epoxides have trouble reacting at such low temperatures. Methods of the present disclosure may form novel copolymers without utilizing conventional methods of endcapping or utilizing temperatures below the ceiling temperature. Unexpectedly, the activators of the present disclosure are capable of copolymerizing oPA at temperatures at or above room temperature, violating expected laws of thermodynamics.

[0053] Referring to FIG. 1, a method 100 of forming a degradable copolymer is illustrated. The method 100 includes the following steps:

[0054] STEP 110, CONTACT O-PHTHALALDEHYDE (OPA) WITH A FIRST MONOMER IN THE PRESENCE OF AN ACTIVATOR AND AN ORGANIC LEWIS BASE OR AN INITIATOR, includes contacting oPA with a first monomer such as a cyclic epoxide, a cyclic episulfide, a cyclic aziridine, and a cyclic ester. STEP 110 is sufficient to form a polymer such as polyethers, polyesters, polyacetals. STEP 110 may include contacting one or more of oPA, the first monomer, the activator, and the organic Lewis base or the initiator with a solvent. Contacting the compounds may be performed in any order. For example, the initiator and activator may be contacted first, followed by the addition of oPA and the first monomer. Contacting may include stirring, mixing, placing two or more components in contact and/or in close proximity, heating, treating, and/or reacting. In one example, the reaction proceeds until the color of the mixture/solution changes from a color (such as yellow) to clear or colorless.

[0055] One example of the first monomer is shown below, where Z may be oxygen, nitrogen, and sulfur. In one example, Ri and R2 may be selected from an alkyl group and an aryl group. The first monomer may be a monomer including two or more hydroxyl groups. The first monomer may be selected from oxiranes, dioxiranes, and cyclic esters. For example, the first monomer may be ethylene oxide.

[0056] In one example, the activator may include one or more alkyl boranes such as trialkyl borane (TAB). In another example, the activator may include one or more of triethylborane (TEB), trialkylaluminum (TAA), and dialkyl zinc. In yet another example, the activator may be selected from an aromatic boron, alkyl aluminum, and an aromatic aluminum. The activator may have multiple functions during the polymerization process. The activator may interact with the growing chain and may activate the monomer. For example, the activator may contact an anion during polymerization sufficient to form an ate complex. The activator may activate the monomer, such as an epoxide, and block copolymerization. In one example, the initiator is selected from benzyl alcohol, tetrabutyl ammonium chloride (TBA-C1), and tetrabutyl ammonium succinate (TBAS). The initiator, which may form an ate complex with the activator, can include salts or organic bases. The salts and organic bases can include organic cations or alkali metals associated or mixed with anions. In one example, bases are selected from the bases of the present disclosure.

[0057] The activator may be selected to achieve one or more of selectively activating the monomer and forming an ate complex with the initiator. The activator may be provided in stoichiometric excess of the initiator. In one example, the ratio of activator to initiator ranges from about 1: 1 to about 7: 1. In another example, the molar ratio of activator to initiator may be about 1 :1, about 2:1, about 3: 1, about 4:1, about 5:1, or even greater. The molar ratio of oPA to the first monomer may range from about 1:50 to about 5:1. In one example, the molar ratio of oPA to the first monomer ranges from 1 :10 to 3:1. In another example, the molar ratio of oPA to the first monomer ranges from 1:3 to 2:1. For example, the molar ratio of oPA to the first monomer may be 1:1.

[0058] oPA may be further contacted with a second monomer sufficient for terpolymerization. In one example, the second monomer may be one or more of a heteroallene monomer and a cyclic anhydride monomer. For example, the heteroallene monomer may be carbon dioxide. For example, terpolymerization may include utilizing oPA, cyclic anhydrides, carbon dioxide, and one or more of cyclic oxiranes, cyclic episulfides, and cyclic aziridine monomers. In one example, the cyclic anhydride includes phthalic anhydride. The molar ratio of oPA to the second monomer may range from about 1:50 to about 10:1. In one example, the molar ratio of oPA to the second monomer ranges from 1:5 to 3:1. In another example, the molar ratio of oPA to the second monomer ranges from 1 :2 to 2 : 1. For example, the molar ratio of oPA to the second monomer may be 1:1.

[0059] In one example, copolymerization/terpolymerization is completed at a temperature above about 15 °C and/or above room temperature (20 °C). For example, the polymerization may be completed at a temperature above 15 °C, above 16 °C, above 17 °C, above 18 °C, above 19 °C, above 20 °C, above 21 °C, above 22 °C, above 23 °C, above 24 °C, above 25 °C, above 26 °C, above 27 °C, above 28°C, above 29 °C, or above 30 °C, or any value therebetween. In another example, polymerization is completed at a temperature ranging from about 15 °C to about 100 °C. In yet another example, polymerization is completed at a temperature ranging from 20 °C to 60 °C. In yet another example, polymerization is completed at a temperature ranging from 25 °C to 45 °C. Advantageously, the polymerization process does not require a cooling process. The polymerization process may include any pressure sufficient to form polymers. For example, the polymerization process may be completed at about ambient pressure. In one example, the polymerization process may be completed at a pressure ranging from 0.01 bar to 15 bar. In another example, the polymerization process is completed at a pressure between about 0.95 bar and about 1.1 bar. In yet another example, the polymerization process is completed at a pressure of about 1 bar.

[0060] Once polymerization is completed, the reaction mixture may be quenched by adding a solvent to the reaction mixture. One example of a solvent is tetrahydrofuran (THF). Other solvents known in the art may be utilized, such as acetone, water, methanol, ethanol. After quenching, a crude polymer may be precipitated into a solvent, such as methanol. In one example, precipitation is completed using water. Following precipitation, the polymer may be dried under vacuum sufficient to obtain a solid. In one example, the polymer may be dried for more than 5 hours sufficient to form the solid. In another example, the polymer may be dried for more than 10 hours sufficient to form the solid. The solid may be a pure, or substantially pure, polymer in the form of a powder. In one example, substantially pure may indicate over 90 % or over 95 % purity of polymer.

[0061] Method 100 may be utilized for producing a polymer according to any one of Reaction Schemes 1, 2, 3, and/or 4. Method 100 may further include treating the formed, degradable copolymer sufficient to decrease the molar mass of the copolymer. For example, treating may include an acid treatment and/or a thermal treatment process. Acid treatment may include contacting the formed copolymer with an acid sufficient to decrease the molar mass of the copolymer. In one example, thermal treatment includes heating the copolymer at/to a temperature above room temperature. In another example, thermal treatment includes heating the copolymer at/to a temperature ranging from 50 °C to 200 °C. In yet another example, thermal treatment includes heating the copolymer at/to a temperature ranging from 100 °C to 150 °C. For example, the copolymer may be heated for 1 or more hours.

[0062] Referring to FIG. 2, a method 200 of forming a copolymer is illustrated. The method 200 includes the following steps:

[0063] STEP 210, CONTACT O-PHTHALALDEHYDE (OP A) WITH A FIRST MONOMER AND A SECOND MONOMER IN THE PRESENCE OF AN ACTIVATOR AND AN ORGANIC LEWIS BASE OR AN INITIATOR, includes contacting oPA with a first monomer such as a cyclic epoxide, a cyclic episulfide, a cyclic aziridine, and a cyclic ester, and with a second monomer such as a heteroallene monomer and a cyclic anhydride monomer. For example, the first monomer may be a monomer described in the present disclosure. Contacting may include stirring, mixing, placing two or more components in contact and/or in close proximity, heating, treating, and/or reacting.

[0064] Method 200 may be utilized to produce a polymer according to any one of Reaction Schemes 3 and/or 4. The first monomer may be any monomer of the present disclosure, such as an oxirane, dioxirane, and a cyclic ester. The second monomer may include one or more of a heteroallene monomer and a cyclic anhydride monomer. A heteroallene monomer may be derived from an allene. Examples of second monomers include carbon dioxide, carbon disulfide, carbonyl sulfide, isocyanate, succinic anhydride, maleic anhydride, dimethylmaleic anhydride, glutaric anhydride, glycolic anhydride, diglycolic anhydride, C6SA, phthalic anhydride, and NorA. In one example, the first monomer is propylene oxide, and the second monomer is carbon dioxide. In another example, the first monomer is propylene oxide and the second monomer is phthalic anhydride.

[0065] In one example, the activator may include one or more alkyl boranes such as trialkyl borane (TAB). In another example, the activator may include one or more of triethylborane (TEB), trialkylaluminum (TAA), and dialkyl zinc. In yet another example, the activator may be selected from an aromatic boron, alkyl aluminum, and an aromatic aluminum. The activator may have multiple functions during the polymerization process. The activator may interact with the growing chain and may activate any of the monomers. For example, the activator may contact an anion during polymerization sufficient to form an ate complex. The activator may activate the monomer, such as an epoxide, and block copolymerization. In one example, the initiator is selected from benzyl alcohol, tetrabutyl ammonium chloride (TBA- Cl), and tetrabutyl ammonium succinate (TBAS). In one example, bases are selected from the bases of the present disclosure, such as a phosphazene base.

[0066] The same temperatures and pressures as method 100 may be utilized for method 200. Further, the quenching and drying process of method 100 may be utilized for method 200. Method 200 may further include treating the formed, degradable polymer sufficient to decrease the molar mass of the polymer. For example, treating may include an acid treatment and/or a thermal treatment process. The treating process may be the same as method 100. Importantly, method 200 includes the terpolymerization of oPA with cyclic anhydrides and/or heteroallene monomers. This terpolymerization process may also occur above the T _c of oPA, which is about -40 °C. Therefore, an extensive and expensive cooling process is not required. Further, these degradable polymers may be utilized for packing, binder applications, coatings, drug delivery, and lithography.

[0067] Referring to FIG. 3, a method 300 of forming a copolymer is illustrated. The method 300 includes the following steps:

[0068] STEP 310, CONTACT O-PHTHALALDEHYDE (OPA) WITH A FIRST MONOMER IN THE PRESENCE OF AN ACTIVATOR, INITIATOR, AND A BASE, includes contacting oPA with a first monomer including two or more hydroxyl groups. The first monomer may be any monomer of the present disclosure. Contacting may include stirring, mixing, placing two or more components in contact and/or in close proximity, heating, treating, and/or reacting. Contacting may include forming a multi-anion from the first monomer and the initiator, sufficient to form the degradable copolymer in more than one direction. In one example, the first monomer includes a diol, and the diol forms a di-anion. In one example, the diol may be selected from alkanediols and glycols. Examples of diols include ethylene glycol, propylene glycol, trimethylene glycol, and cyclohexane- 1,2-diol. The first monomer may include a triol. One example of a triol is glycerol.

[0069] In one example, the activator may include one or more alkyl boranes such as trialkyl borane (TAB). In another example, the activator may include one or more of triethylborane (TEB), trialkylaluminum (TAA), and dialkyl zinc. In yet another example, the activator may be selected from an aromatic boron, alkyl aluminum, and an aromatic aluminum. The activator may have multiple functions during the polymerization process. The activator may interact with the growing chain and may activate any of the monomers. For example, the activator may contact an anion during polymerization sufficient to form an ate complex. The activator may activate the monomer, such as an epoxide, and block copolymerization. In one example, the initiator is selected from benzyl alcohol, tetrabutyl ammonium chloride (TBA- Cl), and tetrabutyl ammonium succinate (TBAS). In one example, bases are selected from the bases of the present disclosure, such as a phosphazene base.

[0070] The same temperatures and pressures as method 100 may be utilized for method 300. For example, method 300 may include polymerization at room temperature (or elevated temperatures) and ambient pressure. Not only does this decrease cost, but polymerization under mild conditions reduces the total steps to polymerize oPA. Method 300 may further include treating the formed, degradable polymer sufficient to decrease the molar mass of the polymer. For example, treating may include an acid treatment and/or a thermal treatment process. The treating process may be the same as method 100. Further, the quenching and drying process of method 100 may be utilized for method 300.

[0071] Methods of the present disclosure provide efficient methods for forming degradable polymers. Accordingly, the methods provide a one-step addition process sufficient to form the polymer. Uniquely, the monomers of the present disclosure at copolymerized with oPA with high conversions. These high conversions are achieved for a variety of monomers, activators, and initiators. Further, these degradable polymers can contribute to decreasing the use of non-degradable polymers. These novel, degradable polymers may be utilized for various applications.

[0072] The degradable polymers of the present disclosure may be utilized for packing, binder applications, coatings, drug delivery, and lithography. In one example, the degradable polymers may be utilized for transient devices and stimuli response materials. Since these polymers are degradable, there is a high demand for these polymers with recent environmental challenges. These degradable polymers may be formed by a quick, one-step polymerization process and may utilize a variety of monomers. Further, the polymerization process may be completed at mild temperatures and pressures. Importantly, the degradable polymers formed from the methods of the present disclosure may be treated to decrease the molar mass. Further, the carbonate content may be tuned from 0 % to 100 %.

Example 1

[0073] Degradable polymers are emerging as prominent materials due to the current use of non-degradable polymeric materials. Degradable polymers may be utilized for transient devices, lithography, and as stimuli response materials. The ceiling temperature of most aldehydes is below room temperature. Conventionally, endcapping the labile hemiacetal chain ends is necessary to prevent depolymerization of polyaldehydes under ambient conditions or elevated temperatures. Further, conventional polymerization of oPA was completed below -40 °C. This cationic polymerization produced oPA polymer “PoPA” rapidly out of control with high molar masses and broader polydispersity. These high molar mass PoPAs are of cyclic structure without an end group. Traditional anionic polymerization required endcapping of the PoPA to avoid depolymerization. In order to modify the thermal, mechanical, and chemical properties of PoPA generated, some conventional methods were devoted to polymerize or copolymerize phthalaldehyde derivatives, where the oPA monomer was substituted by halogens or other functional groups. These applications are very limited due to the unavailability of these monomers and the difficulty of synthesis.

[0074] Accordingly, it is desirable to form polymers at or above room temperature with oPA. Further, it is desirable to form these polymers without an endcapping requirement. oPA was copolymerized with a variety of monomers in the presence of triethyl borane as an activator. In contrast to the copolymerization of oPA at low temperatures, such as below -40 °C, oPA in the present disclosure was copolymerized at more mild conditions to form novel copolymers. Monomers such as cyclic monomers were utilized with an activator to form the degradable copolymers. The degradability was tested using acid and thermal treatments. Further, the carbonate content of formed polyols may be varied by utilizing different CO2 polymerization pressures.

[0075] The results of the copolymerization of cyclic monomers with oPA activated by triethylborane at 25 °C are shown in Table 1. Polymerization was completed in a scintillation vial at 25 °C under argon atmosphere. The conversion was determined by NMR of the reaction mixture. The Mn(xl0 ³ )/PDI was determined by GPC using tetrahydrofuran as the fluent and polystyrene as standard. Entry 1 utilized tBu-P2 as a base. The reaction for entry 12 was carried out in Schlenk tube under argon atmosphere, by sequential addition of PO and oPA (iterative method). For entry 13, first, a polyether PEO block was prepared, followed by LA and oPA copolymerization. For entry 14, polymerization was carried out in a parr reactor under 1 bar CO2 pressure at 40 °C. For entry 16, the reaction was carried out in a scintillation vial at 25 °C, obtaining highly cross-linked material insoluble in organic solvents. The abbreviations in the table are as follows: TBA-C1= tetrabutyl ammonium chloride, TBAS= Tetrabutyl ammonium succinate, PO= propylene oxide, EO= ethylene oxide, BO= 1-butene oxide, 00= 1 -octene oxide, AGE= allyl glycidyl ether, PGE= phenyl glycidyl ether, SO= styrene oxide, LA= L-lactide, PA= phthalic anhydride, and RDGE= resorcinol di-glycidyl ether. Table 1. Copolymerization results of cyclic monomers with orthophthaldehyde (oPA) activated by triethylborane (TEB) at 25 °C.

Entry Initiator M M/oPA[l]/[TEB] Reaction Conversion A n(x10 ³ ) time (%) /PDI

1 Benzyl alcohol PO 100/100/1/2 5h 98 17.3/1.03

2 TBA-CI PO 100/100/1/1 10h 99 17.5/1.03

3 TBA-CI PO 100/100/1/2 5h 99 17.1/1.02

4 TBA-CI PO 200/200/1/2 10h 60 17.0/1.24

5 TBA-CI EO 100/100/1/2 2h 95 12.8/1.02

6 TBA-CI BO 100/100/1/2 12h 70 9.2/1.12

7 TBA-CI OO 100/100/1/2 12h 65 8.9/1.17

8 TBA-CI AGE 100/100/1/2 12h 72 10.6/1.08

9 TBA-CI PGE 100/100/1/2 8h 68 7.8/1.17

10 TBA-CI SO 100/100/1/4 24h 40 2.8/1 .3

1 1 TBAS PO 100/100/1/2 5h 100 18.1/1.03

12 TBAS PO 1000/20/1/2 14h 70 53.8/1.07

13 TBA-CI LA 100/20/1/2 24h 45 5.8Z2.4

14 TBA-CI PO, CO2 1000/100/1/4 48h 85 54.0/1.07

15 TBA-CI PO, PA 200/20/20/1/2 12h 80 12.0/1.2

16 TBA-CI RDGE 50/100/1/2 5h 99

Copolymerization of oPA and PO

[0076] A representative example of a typical synthesis procedure of copolymerization for entry 3, Table 1, is described below. A 20 mL scintillation vial with a magnetic stir bar was dried in the oven at 120 °C and immediately transferred to the glove box under argon. The vial was then charged with the initiator TBA-C1 (0.0277 g, 0.1 mmol) and activator TEB (0.2 mL, IM solution in THF, 0.2 mmol), followed by the addition of 1 mL of THF as a solvent. The monomers oPA (1.34 g, 10 mmol) and PO (0.7 mL, 10 mmol) were then added, and the vial was sealed with a screw cap and stirred at 25 °C for 5 hours. The progress of the reaction was monitored by a visual change in color of the reaction mixture from pale yellow to colorless. After completion, the vial was removed from the glove box, and the reaction mixture was quenched by adding an excess of THF. The crude polymer was precipitated into methanol, followed by overnight drying under vacuum to obtain a pure polymer as a white powder.

[0077] FIG. 4 illustrates a 400 MHz ¹ H NMR spectrum for alternating copolymer P(PO- aZt-oPA) (Table 1, Entry 3), according to some embodiments. The ' H NMR spectrum was completed in CDCL- FIG. 4 also illustrates the corresponding structure of the formed copolymer. FIG. 5 illustrates GPC traces of alternating copolymer P(PO-aZt-oPA) (Table 1, Entry 3) and its degradation after thermal and acid treatment, according to some embodiments. FIG. 5 illustrates the GPC curves for entry 3, entry 3 after hydrochloric acid degradation, and entry 3 after thermal degradation.

[0078] For a typical acid degradation experiment, 1.0 g of a copolymer from entry 3 was dissolved in 5% HC1 in THF and stirred for 10 minutes, and then the crude sample was analyzed by GPC and ^J H NMR. For a typical thermal degradation experiment, 1.0 g of a copolymer from entry 3 was heated in an oven at 125 °C for 5 hours, and then the crude sample was analyzed by GPC and ^J H NMR.

Copolymerization of oPA and PO by sequential addition (iterative method)

[0079] A representative example of a typical synthesis procedure of copolymerization for entry 12, Table 1, is described below. A 50 mL Schlenk tube with a magnetic stir bar was dried in an oven at 120 °C and immediately transferred to the glove box under argon. The Schlenk flask was then charged with the initiator TBAS (0.06 g, 0.1 mmol) and activator TEB (0.2 mL, IM solution in THF, 0.2 mmol), followed by the addition of 1 mL of THF as a solvent. A stock solution of oPA (0.268 g, 2.0 mmol, into 4.7 mL THF) and PO (7.0 mL, 100 mmol into 3 mL THF) were pre-prepared and transferred to separate airtight syringes. The Schlenk tube was sealed with septa, and PO (1 mL THF solution, 10 mmol) was charged from the stock solution and stirred for Ih, followed by the addition of oPA (0.5 mL THF solution, 0.2 mmol) from a syringe stock solution, followed by stirring for an additional 20 minutes. The procedure was sequentially repeated 10 times to obtain a high molecular weight polymer with evenly distributed oPA units in a polymer chain. After completion, the reaction mixture was quenched by adding an excess of THF. The crude polymer was precipitated into water, followed by overnight drying under vacuum to obtain pure polymer.

[0080] FIG. 6 illustrates a 400 MHz ¹ H NMR spectrum for random copolymer P(PO-co- oPA) (Table 1, Entry 12), according to some embodiments. The ' H NMR spectrum was completed in CDCL- FIG. 6 also illustrates the corresponding structure of the formed copolymer. FIG. 7 illustrates GPC curves for TBAS initiated random copolymer P(PO-co-oPA) (Table 1, Entry 12), prepared by sequential polymerization method (iterative method), according to some embodiments. FIG. 7 illustrates the GPC curves for entry 12 and entry 12 after acid degradation. FIG. 8 illustrates a 400 MHz ¹ H NMR spectrum for Table 1, Entry 12, after acid degradation and TFAA modification in CDCL, according to some embodiments. FIG. 8 also illustrates the corresponding structure of the formed copolymer (before and after treatment). FIG. 9 illustrates a 400 MHz ¹⁹ F NMR spectrum for Table 1, Entry 12, after acid degradation and TFAA modification in CDCh, according to some embodiments. FIG. 9 also illustrates the corresponding structure of the formed copolymer (before and after treatment).

Copolymerization of oPA with L-lactide

[0081] A representative example of a typical synthesis procedure of copolymerization for entry 13, Table 1, is described below. A 20 mL scintillation vial with a magnetic stir bar was dried in an oven at 120 °C and immediately transferred to the glove box under argon. The vial was then charged with the initiator TBA-C1 (0.0554 g, 0.2 mmol) and activator TEB (0.4 mL, IM solution in THF, 0.4 mmol), followed by the addition of 1 mL of THF as a solvent. Initially, a short PEG block was prepared by adding EO(1.06 mL, 10 mmol) and stirred for 30 minutes. After the complete consumption of EO monomers, oPA (0.536 g, 4.0 mmol) and L-Lactide (2.88 g, 20 mmol) were then added, and the vial was sealed with a screw cap and stirred at 25 °C for 24 hours. The vial was removed from the glove box, and the reaction mixture was quenched by adding an excess of THF. The crude polymer was precipitated into methanol, followed by overnight drying under vacuum to obtain pure polymer as a white powder.

[0082] FIG. 10 illustrates a 400 MHz ¹ H NMR spectrum for Table 1, Entry 13 in CDCh random copolymer of P(PC-co-oPA), according to some embodiments. FIG. 10 illustrates the corresponding structure of the random copolymer. FIG. 11 GPC curves for TBAS initiated random copolymer P(PC-co-oPA) (Table 1, Entry 13) using 1 bar CO2 pressure, according to some embodiments. FIG. 11 illustrates the GPC curves for entry 14 and entry 14 after acid degradation.

Random Copolymerization of oPA, PO, and CO2

[0083] A representative example of a typical synthesis procedure of copolymerization for entry 14, Table 1, is described below. A 50 mL Parr reactor with a magnetic stir bar was dried in the oven at 120 °C and transferred to the glove box under argon. The reactor was allowed to cool at room temperature and then charged with the initiator TBAS (0.03 g, 0.05 mmol) and activator TEB (0.120 mL, IM solution in THF, 0.2 mmol), followed by the addition of 2 mL of THF as a solvent. Monomers oPA ( 0.67 g, 5.0 mmol) and PO ( 3.5 mL, 50 mmol) were then added, and the reactor was quickly sealed, taken out from the glove box, and CO2 was charged to a pressure of 1.0 bar. The reaction mixture was stirred at 40 °C for 48 hours. The reactor was cooled, the unreacted CO2 was released, and the polymer solution was quenched by diluting with THF. Precipitation in methanol and overnight drying under vacuum at 40 °C were completed. Copolymerization of oPA, anhydride and PO

[0084] A representative example of a typical synthesis procedure of copolymerization for entry 15, Table 1, is described below. A 20 mL scintillation vial with a magnetic stir bar was dried in an oven at 120 °C and immediately transferred to the glove box under argon. The vial was then charged with the initiator TBA-C1 (0.0277 g, 0.1 mmol) and activator TEB (0.2 mL, IM solution in THF, 0.2 mmol), followed by the addition of 1 mL of THF as a solvent. Monomers oPA ( 0.268 g, 2.0 mmol), PA (0.296 g, 2.0 mmol) and PO (1.4 mL, 20 mmol) were then added, and the vial was sealed with a screw cap and stirred at 25 °C for 5 hours. After completion, the vial was removed from the glove box, and the reaction mixture was quenched by adding an excess of THF. The crude polymer was precipitated into a methanol/water mixture, followed by overnight drying under vacuum to obtain pure polymer.

[0085] FIG. 12 illustrates a 400 MHz ¹ H NMR spectrum for Table 1, Entry 15 in CDCh random copolymer of P(PO-co-oPA-PA) (unreacted monomer oPA* and PO ^# ), according to some embodiments. FIG. 12 also illustrates the corresponding structure of the formed random copolymer.

Copolymerization of oPA with resorcinol di-glycidyl ether

[0086] A representative example of a typical synthesis procedure of copolymerization for entry 16, Table 1, is described below. A 20 mL scintillation vial with a magnetic stir bar was dried in an oven at 120 °C and immediately transferred to the glove box under argon. The vial was then charged with the initiator TBA-C1 (0.0277 g, 0.1 mmol) and activator TEB (0.2 mL, IM solution in THF, 0.2 mmol), followed by the addition of 1 mL of THF as a solvent. Monomers oPA (1.34 g, 10 mmol) and recorcinol di-glycidyl ether (0.7 mL, 10 mmol) were then added, and the vial was sealed with a screw cap and stirred at 25 °C for 5 hours. After completion, an insoluble colorless material was obtained, which was washed with methanol and dried overnight under vacuum.

Additional ¹ H NMR for formed copolymers

[0087] FIG. 13 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 5 in CDCh random copolymer of P(EO-co-oPA), according to some embodiments. The ¹ H NMR spectrum was completed in CDCh- FIG. 13 also illustrates the corresponding structure of the formed random copolymer.

[0088] FIG. 14 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 6 in CDCh alternating copolymer of P(BO-aZt-oPA), according to some embodiments. FIG. 14 also illustrates the corresponding structure of the formed copolymer. [0089] FIG. 15 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 7 in CDCh alternating copolymer of P(OO-aZt-oPA), according to some embodiments. FIG. 15 also illustrates the corresponding structure of the formed copolymer.

[0090] FIG. 16 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 8 in CDCh random copolymer of P( AGE-co-oP A), according to some embodiments. FIG. 16 also illustrates the corresponding structure of the formed copolymer.

[0091] FIG. 17 illustrates a 400 MHz ' H NMR spectrum for Table 1, Entry 9 in CDCh alternating copolymer of P(PGE-aZt-oPA), according to some embodiments. FIG. 17 also illustrates the corresponding structure of the formed copolymer.

[0092] FIG. 18 illustrates a 400 MHz ¹ H NMR spectrum for Table 1, Entry 10 in CDCh random copolymer of P(SO-co-oPA), according to some embodiments. FIG. 18 also illustrates the corresponding structure of the formed copolymer.

Discussion of Possible Embodiments

[0093] According to one aspect, a degradable copolymer includes: wherein Q is a repeating unit selected from one of the following: wherein J is selected from one of the following: and wherein Ri, R2, and R3 are selected from alkyl and aryl groups, Z is selected from oxygen, nitrogen, and sulfur, and m, n, and p are 1 or greater. [0094] The degradable copolymer of the preceding paragraph can optionally include, additionally and/or alternatively any one or more of the following features, configurations and/or additional components.

[0095] The degradable copolymer may include the product of copolymerizing o- phthalaldehyde (oPA) with a cyclic epoxide, cyclic episulfide, cyclic aziridine, or cyclic ester monomer.

[0096] The degradable copolymer may include the product of copolymerizing o- phthalaldehyde (oPA) with a monomer in the presence of an alkyl borane.

[0097] The degradable copolymer may include the product of copolymerizing o- phthalaldehyde (oPA) at a temperature at or above 15 °C.

[0098] According to one aspect, a method of forming a degradable polymer includes contacting o-phthalaldehyde (oPA) with a first monomer in the presence of an activator and an organic Lewis base or an initiator, wherein the first monomer includes a monomer selected from a cyclic epoxide, a cyclic episulfide, a cyclic aziridine, and a cyclic ester.

[0099] The method of the preceding paragraph can optionally include, additionally and/or alternatively any one or more of the following features, configurations and/or additional components.

[00100] The activator may include an alkyl borane, aromatic borane, alkyl aluminum, or aromatic aluminum.

[00101] The activator may be selected from triethyl borane, trialkyl aluminum, and dialkyl zinc.

[00102] The organic Lewis base may be selected from: wherein R is an alkyl or aryl group.

[00103] The initiator may be selected from benzyl alcohol, tetrabutylammonium chloride, and tetrabutylammonium succinate.

[00104] The cyclic epoxide may include an oxirane selected from:

wherein R is an alkyl or aryl group.

[00105] The cyclic epoxide may include a dioxirane selected from:

[00106] The cyclic ester may include one of the following: [00107] The method may further include contacting oPA with a second monomer selected from a cyclic anhydride monomer and a heteroallene monomer.

[00108] The second monomer may include one of the following:

[00109] The heteroallene monomer may include a monomer selected from carbon dioxide, carbon disulfide, carbonyl sulfide, and isocyanate.

[00110] The degradable polymer may be formed at a temperature greater than about 15 °C.

[00111] The method may further include treating the degradable polymer to decrease the molar mass, wherein treating includes one or more of contacting the polymer with an acid and heating the copolymer at a temperature above 100 °C.

[00112] According to one aspect, a method of forming a degradable copolymer includes contacting o-phthalaldehyde (oPA) with a first monomer in the presence of an activator, initiator, and a base, wherein the first monomer includes two or more hydroxyl groups, and wherein contacting includes forming a multi-anion from the first monomer and the initiator, sufficient to form the degradable copolymer in more than one direction.

[00113] The method of the preceding paragraph can optionally include, additionally and/or alternatively any one or more of the following features, configurations and/or additional components.

[00114] The first monomer may include a diol and the multi-anion is a di-anion.

[00115] The method may further include contacting oPA with a second monomer selected from a cyclic anhydride monomer and a heteroallene monomer.

[00116] While the disclosure has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted for elements thereof without departing from the scope of the embodiment(s). In addition, many modifications may be made to adapt a particular situation or material to the teachings of the embodiment(s) without departing from the essential scope thereof. Therefore, it is intended that the disclosure is not limited to the disclosed embodiment(s), but that the disclosure will include all embodiments falling within the scope of the appended claims. Various examples have been described. These and other examples are within the scope of the following claims.