Cross Reference to Related Applications

This application claims priority to European patent application No. 21306157.5 filed on August 26, 2021 , the whole content of this application being incorporated herein by reference for all purposes.

Field of the Disclosure

The present disclosure relates to soluble liquid crystalline polyesters (LCPs) exhibiting low dielectric constant and dissipation factors and articles containing the said polyesters, such articles being suitable for mobile electronic device components, for example films or structural components. The present disclosure further relates to solutions comprising the LCPs and use of the said solutions for the manufacture of films or mobile electronic device articles or components.

Background of the Disclosure

Due to their reduced weight and high mechanical performance, polymer compositions are widely used to manufacture mobile electronic device components. Thus, there exists a high demand from the market for polymer compositions useful for the manufacture of mobile electronic device components, especially polymer compositions having improved dielectric performance (i.e. , low dielectric constants and dissipation factors).

In mobile electronic devices, the material forming the various components and housing can significantly degrade wireless radio signals (e.g. 1 MHz, 2.4 GHz, 5.0 GHz, 20.0 GHz frequencies) transmitted and received by the mobile electronic device through one or more antennas. The dielectric performances of the material to be used in mobile electronic devices can be determined by measuring the dielectric constant and dissipation factor of a material. The dielectric constant represents the ability of the material to interact with the electromagnetic radiation and disrupt electromagnetic signals (e.g. radio signals) travelling through the material.

Accordingly, the lower the dielectric constant of a material at a given frequency, the less the material disrupts the electromagnetic signal at that frequency. Dissipation factor is the reciprocal of the ratio between a material’s capacitive reactance to its resistance at a specified frequency. It measures the electromagnetic energy absorbed and lost (power dissipation) when electromagnetic radiation is applied. The lower the dissipation factor, the less the material absorbs electromagnetic radiation and dissipates it, typically as heat.

Liquid crystalline polyesters, or LCPs, are a class of polymers that exhibit promising dielectric properties, making such LCPs potential candidates for use in mobile electronic device applications. However, processing of LCP polymers into articles or structural components, such as films, is very challenging due to the liquid crystalline nature of the backbone (anisotropic properties are different in different film directions (machine vs. transverse direction)). Moreover, the high melting temperatures and low melt strength of LCPs limits the use of common melt processing techniques. Accordingly, a very complex biaxial melt processing technique is typically used to overcome the anisotropic nature commonly seen in processed LCPs.

A simpler technique for producing films of polymers is solution casting or solution coating a film using a dissolved polymer in a volatile solvent which can be removed during the process. However, very few examples of LCPs exist that have solubility, and even fewer, if any, having the dielectric and thermal properties required for mobile electronic device applications. LCPs tend to be insoluble in common lab and process solvents, which make them difficult to process by solution methods.

Some LCPs are known. For example, Kricheldorf et al. in “LC-Polyimides - 14. Thermotropic Copoly(ester-imide)s derived from N-(3'-hydroxyphenyl)trimellitimide and 4-Hydroxybenzoic acid or 6-Hydroxy-2-naphthoic Acid”, Eur. Polym. J., Vol. 30, No. 4, pp. 549-556, 1994, describe some LCP/amorphous polymers, but does not disclose any properties useful for easy processing, such as solubility, or any properties useful for mobile electronic device applications, such as dielectric performance. Thus, there is an ongoing need for the development of compositions and materials that are easier to process into films or mobile electronic device articles or components while also exhibiting desirable dielectric performance, i.e. , low dielectric constant and dissipation factor.

Summary of the disclosure

This objective, and others which will become apparent from the following detailed description, is met, in whole or in part, by the compositions, materials, methods and/or processes of the present disclosure.

In a first aspect, the present disclosure relates to a mobile device article or component having a polymer comprising recurring units of formula (I):

(I), and recurring units of formula (II): wherein Ar is a C ₆ -C ₁₈ arylene group.

In a second aspect, the present disclosure relates to a solution comprising:

- a polymer comprising recurring units of formula (I):

(I), and recurring units of formula (II): wherein Ar is a C ₆ -C ₁₈ arylene group; and

- a solvent.

In a third aspect, the present disclosure relates to the use of the solution described herein for the manufacture of a film or a mobile electronic device article or component, or for the manufacture of an automotive, aeronautics or drone article or component.

Detailed Description

As used herein, the terms “a”, “an”, or “the” means “one or more” or “at least one” and may be used interchangeably, unless otherwise stated.

As used herein, the term “and/or” used in a phrase in the form of “A and/or B” means A alone, B alone, or A and B together.

As used herein, the term “comprises” includes “consists essentially of” and “consists of.” The term “comprising” includes “consisting essentially of” and “consisting of.” “Comprising”, which is synonymous with “including,” “containing,” or “characterized by,” is intended to be inclusive or open-ended and does not exclude additional, unrecited elements or steps. The transitional phrase “consisting essentially of’ is inclusive of the specified materials or steps and those that do not materially affect the basic characteristic or function of the composition, process, method, or article of manufacture described. The transitional phrase “consisting of” excludes any element, step, or component not specified.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this specification pertains.

As used herein, and unless otherwise indicated, the term “about” or “approximately” means an acceptable error for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined. In certain embodiments, the term “about” or “approximately” means within 1 , 2, 3, or 4 standard deviations. In certain embodiments, the term “about” or “approximately” means within 50%, 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1 %, 0.5%, or 0.05% of a given value or range.

Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations.

The term and phrases “invention,” “present invention,” “instant invention,” and similar terms and phrases as used herein are non-limiting and are not intended to limit the present subject matter to any single embodiment, but rather encompasses all possible embodiments as described. As used herein, the phrase “mobile device article or component” is understood to mean a “mobile device article” or a “mobile device component”, unless explicitly stated otherwise.

Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

In the first aspect, the present disclosure is related to a mobile device article or component having a polymer comprising recurring units of formula (I): and recurring units of formula (II): wherein Ar is a C ₆ -C ₁₈ arylene group.

The mobile device article or component may be a mobile electronic device article or component or an automotive, aeronautics or drone article or component.

Generally, the polymer comprising recurring units of formula (I) and recurring units of formula (II) is a liquid crystalline polyester (LCP) polymer. It has been discovered that such polymers can easily be processed into mobile electronic device articles or components, such as films, while also exhibiting desirable dielectric performance, such as low dielectric constant and/or dissipation factor.

The term “arylene” as used herein refers to a divalent unsaturated hydrocarbon radical containing one or more six-membered carbon rings in which the unsaturation may be represented by three conjugated double bonds. Arylene radicals include monocyclic arylenes and polycyclic arylenes. “Polycyclic arylene” refers to a divalent unsaturated hydrocarbon radical containing more than one six-membered carbon ring in which the unsaturation may be represented by three conjugated double bonds wherein adjacent rings may be linked to each other by one or more bonds, divalent bridging groups, such as sulfoxides (-SO-), sulfones (-SO2-), ethers (-O-), carbonyls (-CO-), thioethers (-S-), alkylenes, alkenylenes, and the like, or may be fused together. Arylene radicals may be substituted at one or more carbons of the ring or rings with hydroxyl, cyano, alkyl, alkoxyl, alkenyl, halo, haloalkyl, monocyclic aryl, amino, -(C=O)-alkyl, -(C=O)O-alkyl, -(C=O)-haloalkyl, or -(C=O)-(monocyclic aryl). Examples of arylene radicals include, but are not limited to, phenyl, styrylbenzene phenyl, (phenylsulfonyl)phenyl, phenoxyphenyl, phenylalkylphenyl, phenylcarbonylphenyl, biphenyl, triphenyl, anthracenyl, naphthyl, phenanthrenyl, and the like.

In an embodiment, Ar is selected from the group consisting of:

In another embodiment, Ar is

Unless otherwise indicated, the bonds that are not connected to a specific carbon in the above arylene groups are not limited as to their position on the aromatic rings.

The amount of the recurring unit of formula (I) is not particularly limited. However, in an embodiment, the polymer comprises from 70 to 95 mol. % of the recurring unit of formula (I), relative to the total amount of the polymer.

Similarly, the amount of the recurring unit of formula (II) is not particularly limited. However, in an embodiment, the polymer comprises from 5 to 30 mol. % of the recurring unit of formula (II), relative to the total moles of the polymer.

The relative molar concentration of the recurring unit of formula (I) to the recurring unit of formula (II) in the polymer of the mobile device article or component is not limited. However, in an embodiment, the relative molar concentration of the recurring unit of formula (I) to the recurring unit of formula (II), is at least 60/40, typically at least 70/30, relative to the total amount of recurring units of formula (I) and recurring units of formula (II).

In an embodiment, the recurring unit of formula (II) is a recurring unit of formula (Ila):

The polymer of the mobile device article or component may further comprise other repeating units. In an embodiment, the polymer of the mobile device article or component further comprises recurring units of formula (III), [-O-AH-O-], and/or recurring units of formula (IV), [-OOC-Ar2-COO-], wherein AH and Ar2 are each, independently, a C ₆ -C ₁₈ arylene group.

Recurring units of formula (III) are derived from aromatic diols of formula (Illa), HO- AH-OH, in which AH is a C ₆ -C ₁₈ arylene group.

Recurring units of formula (IV) are derived from aromatic acids of formula (IVa), HOOC-Ar2-COOH, in which Ar2 is a C ₆ -C ₁₈ arylene group.

In an embodiment, AH and Ar2 are each, independently, selected from the group consisting of:

The polymer of the mobile device article or component may further comprise recurring units of formula (V), [-O-Ar ₃ -COO-], wherein Ars is a C ₆ -C ₁₈ arylene group, typically C ₁₀ -C ₁₈ arylene group. Recurring units of formula (V) are derived from hydroxyacids of formula (Va), HO-Ar ₃ -COOH, in which Ars is a C ₆ -C ₁₈ arylene group, typically C ₁₀ -C ₁₈ arylene group.

Ara is selected from the group consisting of:

In an embodiment, the polymer consists of the recurring units of formula (I) and the recurring units of formula (II).

The polymer of the mobile device article or component may be made according to any suitable process known to those of ordinary skill in the art. Typically, the polymer is produced by the polycondensation of 6-hydroxy-2-naphthoic acid (HNA), or an acetylated derivative thereof, and a compound having formula (lib): wherein Ar is as defined herein, or an acetylated derivative thereof.

In an embodiment, the polymer results from the condensation of: a) from 70 to 95 mol. % of 6-hydroxy-2-naphthoic acid (HNA) and/or 6- acetoxy-2-naphthoic acid (AcHNA), and b) from 5 to 30 mol. % of 2-(3-hydroxyphenyl)-1 ,3-dioxoisoindoline-5- carboxylic acid (IM3P) and/or 2-(3-acetoxyphenyl)-1 ,3-dioxoisoindoline-5- carboxylic acid (AclM3P).

The mobile device article or component may further comprise one or more additives that impart beneficial properties to the mobile device article or component. Suitable additives may be selected from the group consisting of fillers (including reinforcing agents), tougheners, impact modifiers, plasticizers, colorants, surfactants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, anti-drip agents, nucleating agents, chain-extenders, capping agents, laser activatable compounds, thermally conductive fillers, dielectric modifiers, and antioxidants.

Fillers (including reinforcing agents, also called reinforcing fibers or fillers) may be selected from fibrous and particulate reinforcing agents. A fibrous reinforcing filler is considered herein to be a material having length, width and thickness, wherein the average length is significantly larger than both the width and thickness. Generally, such a material has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness of at least 5, at least 10, at least 20 or at least 50. The filler may generally be selected from mineral fillers (such as talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate), glass fibers, carbon fibers, synthetic polymeric fibers, aramid fibers, aluminum fibers, titanium fibers, magnesium fibers, boron carbide fibers, rock wool fibers, steel fibers and inosilicates (e.g., wollastonite). The fillers may be, for example, low dielectric constant fiber filler, hollow fillers, particulate fillers, and the like. The fillers may be electrically and non-electrically thermally conductive fillers, such as boron nitride, zinc oxide or graphene.

Notably, suitable low dielectric constant fillers may have a Dk of less than 5.0 (about 4.5) at a frequency of from 1 megahertz (MHz) to 1 GHz and a Df of less than about 0.002 at a frequency of from 1 MHz to 1 GHz. Low dielectric constant particulate fillers include, but are not limited to, polymer particles, such as PTFE particles, LCP particles, including particles of the polymer described herein, and the like.

Low dielectric constant fiber fillers include, but are not limited to, low dielectric constant glass fiber filler. A suitable example of a low dielectric constant filler is a dielectric glass fiber having a Dk of less than 5.0 at a frequency of from 1 MHz to 1 GHz and a Df of less than about 0.002 at a frequency of from 1 MHz to 1 GHz.

Other exemplary glass fibers include, but are not limited to, E-glass, S-glass, AR- glass, T-glass, D-glass, R-glass, and combinations thereof.

The shape and size of suitable glass fibers, such as low dielectric constant glass fibers, are not limited. The fibers may include milled or chopped glass fibers. They may be in the form of whiskers or flakes. They may also be short glass fiber or long glass fiber. The glass fibers may have a length of about 4 mm (millimeter) or longer are referred as to long fibers, and fibers shorter than this are referred to as short fibers.

The glass fibers, including the low dielectric constant glass fiber, may have a round, flat, or irregular cross-section. Glass fibers having non-round cross-sections may be used. Alternatively, the glass fiber may have circular cross-sections. The diameter of the glass fiber may, for example, be from about 1 to about 15 pm. More specifically, the diameter of the low dielectric constant glass fiber may for example be from about 4 to about 10 pm. Flat glass fibers may also be used, for example flat glass fibers from Nitto Boseki Co., LTD (CSG 3PA-830). Suitable fillers may be surface-treated with a surface treatment agent containing a coupling agent to improve adhesion to the polymer base resin. Suitable coupling agents include, but are not limited to, silane-based coupling agents, titanate-based coupling agents or a mixture thereof. Applicable silane-based coupling agents include aminosilane, epoxysilane, amidesilane, azidesilane and acrylsilane. Organo metallic coupling agents, for example, titanium or zirconium-based organo metallic compounds, may also be used.

Hollow fillers may, for example, be hollow glass spheres, hollow glass fibers, or hollow ceramic spheres. Exemplary hollow glass spheres have a density of from 0.2 grams per cubic centimeter (g/cm ³ ) to about 0.6 g/cm ³ Typically, suitable hollow glass spheres have a diameter of from 5 pm to 50 pm.

Tougheners, also called impact modifiers, are generally low glass transition temperature (Tg) polymers, with a Tg for example below room temperature, below 0°C or even below -25°C. As a result of their low Tg, tougheners are typically elastomeric at room temperature. Tougheners can be functionalized polymer backbones. For example, suitable tougheners may be siloxane-based.

The polymer backbone of the toughener may also be selected from elastomeric backbones comprising polyethylenes and copolymers thereof, e.g. ethylene-butene; ethylene-octene; polypropylenes and copolymers thereof; polybutenes; polyisoprenes; ethylene-propylene-rubbers (EPR); ethylene-propylene-diene monomer rubbers (EPDM); ethylene-acrylate rubbers; butadiene-acrylonitrile rubbers, ethylene-acrylic acid (EAA), ethylene-vinylacetate (EVA); aery Ion itrile- butadiene-styrene rubbers (ABS), block copolymers styrene ethylene butadiene styrene (SEBS); block copolymers styrene butadiene styrene (SBS); core-shell elastomers of methacrylate-butadiene-styrene (MBS) type, or mixtures thereof.

When the toughener is functionalized, the functionalization of the backbone can result from the copolymerization of monomers which include the functionalization or from the grafting of the polymer backbone with a further component. Notable examples of functionalized tougheners are terpolymers of ethylene, acrylic ester and glycidyl methacrylate, copolymers of ethylene and butyl ester acrylate; copolymers of ethylene, butyl ester acrylate and glycidyl methacrylate; ethylene- maleic anhydride copolymers; EPR grafted with maleic anhydride; styrene copolymers grafted with maleic anhydride; SEBS copolymers grafted with maleic anhydride; styrene-acrylonitrile copolymers grafted with maleic anhydride; and ABS copolymers grafted with maleic anhydride.

The mobile device article or component may comprise other conventional additives commonly used in the art, including plasticizers, colorants, pigments (e.g. black pigments such as carbon black and nigrosine), antistatic agents, dyes, lubricants (e.g. linear low density polyethylene, calcium or magnesium stearate or sodium montanate), thermal stabilizers, light stabilizers, flame retardants, nucleating agents, mold release agents and antioxidants.

Exemplary mold release agents include, but are not limited to, metal stearate, stearyl stearate, pentaerythritol tetrastearate, beeswax, montan wax, paraffin wax, or the like, or combinations including at least one of the foregoing mold release agents.

The mobile device article or component may be produced according to any method known to those of ordinary skill in the art, typically from compositions comprising the polymer described herein. It has been discovered that the polymers described herein can not only be easily processed into mobile electronic device articles or components, such as films, but also exhibit desirable dielectric performance, such as low dielectric constant and/or dissipation factor.

Exemplary methods for manufacturing the mobile device article or component include, but are not limited, injection molding, extrusion, compression molding, thermoforming, such as sheet thermoforming, vacuum forming, pressure forming, trapped sheet forming, steam pressure forming; liquid resin casting, transfer molding, and additive manufacturing, such as 3D printing.

In an embodiment, the mobile device article or component is in the form of a film, for example, for use as flexible printed circuit boards (FPCs). The polymer or a composition containing the polymer may also be injection molded for structural components of microelectronics and smart devices, mobile electronic device, i.e. , an electronic device that is intended to be conveniently transported and used in various locations and/or to be wearable, portable, hand-held or otherwise carried by a person. As used herein, the adjective “electronic” in the phrase “mobile electronic device” denotes a device that contains electronic components or electronic packages. A mobile electronic device can include, but is not limited to, a mobile phone, a personal digital assistant (“PDA”), a laptop computer, a tablet computer, a wearable computing device (e.g., a smart watch, smart glasses and the like), a camera, a portable audio player, wireless audio devices, a portable radio, global position system receivers, and portable game consoles.

The mobile device article or component may, for example, comprise a radio antenna. Herein, radio antennas are antennas capable of sending and receiving electromagnetic signals at radio frequencies. Radio antennas include, for example, those suitable for cellular, WiFi, Bluetooth, and RFID communications, and the like. The mobile device article or component may also be an antenna housing.

In some embodiments, the mobile device article or component may be a mounting component with mounting holes or other fastening device, including but not limited to, a snap fit connector between itself and another component of the mobile electronic device, including but not limited to, a circuit board, a microphone, a speaker, a display, a battery, a cover, a housing, an electrical or electronic connector, a hinge, a radio antenna, a switch, or a switchpad. In some embodiments, the mobile electronic device can be at least a portion of an input device.

In some embodiments, the mobile device article or component is used in transportation, for example, in automotive applications (e.g. smart car/intelligent car, such as those with 5G capabilities), aeronautics and drones.

The mobile device article or component described herein can withstand the assembly processing steps typically found in the microelectronic manufacturing space. Various lamination/surface mount technologies (SMT) use temperatures above 260°C. Thus, it is advantageous for polymers used in mobile device articles or components to have a Tm above 255°C. In some embodiments, the Tm of the polymer in the mobile device article or component is from 270 °C to 350 °C, typically 280 °C to 330 °C. Tm may be determined using differential scanning calorimetry (DSC) by methods and instrumentation known those of ordinary skill in the art.

The mobile device article or component can be characterized by its dielectric properties, particularly dielectric constant (DK or s) and dissipation factor (DF). The dielectric constant and dissipation factor may be determined using methods and instrumentation known to those of ordinary skill in the art. One suitable method for measuring dielectric constant and dissipation factor of the mobile device article or component is using a Split Cylinder Resonator (SCR) according to the method described in IPC-TM-6502.5.5.13.

In an embodiment, the mobile device article or component has:

- a dielectric constant £ at 20 GHz equal to or of less than 3.6, and/or

- a dissipation factor (Df) at 20 GHz of less than 0.0032, typically less than 0.0020, as measured in the in-plane direction on 4 cm x 4 cm x 150 pm (thickness) films obtained from the “dry-as-molded’ compression molded films, using a Split Cylinder Resonator (SCR) according to IPC-TM-6502.5.5.13.

In the second aspect, the present disclosure relates to a solution comprising:

- a polymer comprising recurring units of formula (I):

(I), and recurring units of formula (II):

wherein Ar is a C ₆ -C ₁₈ arylene group; and

- a solvent.

Very few examples of LCPs exist that have solubility, and even fewer, if any, having the dielectric and thermal properties required for mobile electronic device applications. LCPs tend to be insoluble in common lab and process solvents, which make them difficult to process by solution methods. However, it was surprisingly discovered that polymers comprising recurring units of formula (I) and recurring units of formula (II) as described herein are soluble in particular solvents to form solutions from which articles, such as films, may be made by solution processing.

Suitable solvents are polar aprotic solvents. As understood by those of ordinary skill in the art, a polar aprotic solvent is a solvent that lacks any acidic protons and is polar.

In an embodiment, the solvent is a polar aprotic solvent, typically selected from N- methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), 1 ,3-dimethyl-2- imidazolidinone (DMI), N,N'-dimethylpropyleneurea (DMPLI), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), acetonitrile, dimethyl-2- methyl glutarate, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, dimethyl glutarate, dimethyl succinate, dimethyl adipate, and mixtures thereof.

The amount of the polymer comprising recurring units of formula (I) and recurring units of formula (II) in the solution is not particularly limited so long as it is soluble in the solvent. However, in an embodiment, the concentration of the polymer is 0.1 to 20 %, typically 1 to 10 %, more typically 2 to 5%, by weight of the solution. In the third aspect, the present disclosure relates to the use of the solution described herein for the manufacture of a film or a mobile electronic device article or component, or for the manufacture of an automotive, aeronautics or drone article or component.

The solutions of the present disclosure may be used to produce articles, such as films, by solution processing. The use of the solutions in creating varnishes and/or coatings, optionally containing additives, is also contemplated. Suitable additives may be those described hereinabove and selected from the group consisting of fillers (including reinforcing agents), tougheners, impact modifiers, plasticizers, colorants, surfactants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, anti-drip agents, nucleating agents, chain-extenders, capping agents, laser activatable compounds, thermally conductive fillers, dielectric modifiers, and antioxidants. For instance, a low DF filler, such as a low DF particulate filler, can be dispersed in the solution.

A suitable use would include depositing a layer of the solution described herein by, for example, casting, spray coating, spin coating, gravure coating, curtain coating, dip coating, slot-die coating, inkjet printing, gravure printing, or screen printing, on a substrate and removing the solvent from the layer. Typically, the solvent is removed from the layer by allowing the solvent component of the layer to evaporate. The substrate supported layer may be subjected to elevated temperature and/or reduced pressure to encourage evaporation of the solvent. The substrate may be rigid or flexible and may comprise, for example, a metal, a polymer, a glass, a paper, or a ceramic material.

The articles, methods and processes according to the present disclosure are further illustrated by the following non-limiting examples.

Examples

Example 1. Synthesis of LCP resin A Reactions were performed in a dried 100 mL round-bottomed flask equipped with an overhead stirrer, nitrogen inlet, and distillation neck attached to a receiving flask. 12.17 g of acetoxy-2-naphthoic acid (AcHNA; 70 mol %) and 7.37 g of 2-(3- acetoxyphenyl)-1 ,3-dioxoisoindoline-5-carboxylic acid (AclM3P; 30 mol %) were added. Subsequent degassing with vacuum and N2 gas purging (3x) produced an oxygen-free environment. The contents were then heated to 245 °C to melt the monomers over 30 min. The temperature was then heated at 1 .0 °C/min to 320 °C and held at the temperature for 15 min. House vacuum was then applied to promote removal of acetic acid condensate for 0.5-1 h followed by application of high vacuum, reaching 0.1-1 mmHg. The reaction was held under high vacuum until no noticeable condensate was seen leaving the reaction and the polymer sample solidified around the stir blade. The sample was subsequently cooled and retrieved from the stir blade.

Comparative Example 1. Synthesis of LCP polymer B

An LCP polymer was synthesized according the procedure of Example 1 , except that AcHNA was replaced with 4-acetoxybenzoic acid (Ac4HBA). 11 .56 g (70 mol %) of Ac4HBA and 8.94 g (30 mol %) of AclM3P was used.

Comparative Example 2. Synthesis of LCP polymer C

An LCP polymer was synthesized according the procedure of Example 1 , except that AclM3P was replaced with Ac4HBA. 15.58 g (70 mol %) of AcHNA and 5.23 g (30 mol %) of Ac4HBA was used.

Example 3. Formation of films

LCP samples were dried at 100 °C overnight before use. Compression molding utilized two stainless steel plates layered with Kapton films and an aluminum shim to control thickness (0.004”). Samples were heated for approximately 3 min at Tm +5 °C before placing the top plate. The sandwich was centered in the press and it was closed to ensure contact with both upper and lower platens. After 2 min of heating at Tm +5 °C, four press-release-press cycles with 2 tons of force for the first two cycles and 4 tons of force for the last two cycles finished the film compression molding procedure. The sandwich was immediately removed from the press and placed on a cool benchtop and allowed to return to ambient temperature over at least 1 h. The films were then removed from the sandwich and placed in an inert N2 oven and annealed. The LCP resin A of Example 1 was annealed at 260 °C for 16 h, and resins B and C of Comparative Examples 1 and 2, respectively, were annealed at 275 °C for 16 h.

Example 4. Properties of LCP polymers

Differential scanning calorimetry (DSC) was used to measure thermal transitions. Differential scanning calorimetry (DSC) revealed thermal transitions using a TA Instruments Q10 DSC, calibrated using indium (MP = 156.60 °C), and maintaining a N2 gas flow of 50 mL/min. A heat, cool, heat cycle was employed utilizing a heating and cooling rate of 20 °C/min. Melting temperature (Tm) was determined using the maximum of the endothermic peak on the first heating cycle.

Microwave dielectric properties (dielectric constant, DK, and dissipation factor, DF) were measured using a split cylinder resonator (KEAD 20GHz SCR) operating at 20 GHz, following IPC-TM-6502.5.5.13. DSC and dielectric properties of the LCP polymers are summarized in Table 1 below.

Table 1.

Example 5. Solutions of LCP polymers

Solutions of the LCP polymers were attempted by placing 5 wt % of LCP powder into a vial and adding 95 wt % of N-Methyl-2-pyrrolidone (NMP). The sample was then heated to 120 °C for 6 h. The sample was then checked for any powder or noticeable particulates remaining. Solubility results are summarized in Table 2 below.

Table 2.

As shown in Table 2, only LCP resins A and B were soluble in NMP. Considering both Tables 1 and 2, LCP resin A displays a unique combination of solubility in NMP, thermal transitions and dielectric performance not seen in the comparative LCP compositions (B & C).