Method for forming polyimide precursors

Abstract

A polyisoimide can be formed by reacting a dianhydride with a diamine to form a polyamic acid wherein the mole ratio of amine groups to anhydride groups is from 0.7:1 to 1:1, and reacting the polyamic acid with a sulfonyl-containing dehydrating agent and a tertiary amine base. A Fourier transfer infrared spectroscopy of the reaction product can show a peak intensity ratio (ratio of maximum absorption intensity or ratio of peak heights) on Fourier Transform Infrared Spectroscopy (FTIR) of a peak indicative of polyisoimide at 1800-1803 cm-1 to a peak indicative of polyimide at 1780-1783 cm-1 in the reaction product greater than at least 1.3:1.

Description

Method for Forming Polyimide Precursors CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application which claims priority to U.S. Provisional Patent Application No.63 / 666,419, filed July 1, 2024, which is incorporated by reference herein in its entirety. FIELD OF THE INVENTION

[0002] The present invention relates to a method of forming polyisoimides useful in forming polyimide precursors, such as polyamic acids and / or polyamic acid esters. BACKGROUND OF THE INVENTION

[0003] Polyimide precursors such as polyamic acids and / or polyamic acid esters are useful in electronic applications as a dielectric layer or film in such devices as capacitors and semiconductors. Photopolymerizable polyimide precursors are widely used in the semiconductor industry. For use in the electronics industry the polyimide precursors must be pure (e.g., free of problematic by-products).

[0004] U.S.4,551,522 discloses a multi-step method of making photopolymerizable aromatic polyamic acid derivatives that requires the formation of a polyisoimide intermediate in the process. The reagent used to form the polyisoimide in the process is either a N,N’- dihydrocarbyl-substituted carbodiimide (commonly N,N’-dicyclohexyl carbodiimide, DCC) or trifluoroacetic acid anhydride. These reagents are called dehydrating agents since formation of the isoimide ring produces one molecule of water. It is believed the dehydrating agent acts by absorbing or extracting water formed during the ring closure. A dehydrating reagent can also form an imide ring in the polymer chain instead of an isoimide since the cyclization to an imide also produces one molecule of water. See also Roderick [“Action of Trifluoroacetic Anhydride on N-Substituted Amic Acids,” William R. Roderick and Parshotam L. Bhatia, J. Org. Chem. (1963), 28, pp.2018-2024.] which disclosed that of all dehydrating reagents tested at that time only trifluoroacetic acid anhydride and DCC were known to primarily form isoimide structures in small molecules. Other dehydrating agents formed primarily imides or were known to form a mixture of both imides and isoimides.

[0005] In the case of the use of a carbodiimide, such as DCC, the U.S.4,551,522 discloses that the resulting urea byproduct can be removed by an extra purification step such as filtration but fails to disclose the resulting purity of the polyamic acid ester product. In fact, removal of the byproduct urea can be challenging and expensive because the ureas arepartially soluble in the synthesis solvent. As a result, a single filtration alone is inadequate to provide the desired purity.

[0006] Use of trifluoroacetic acid anhydride to form the polyisoimide intermediate produces a trifluoroacetic acid byproduct. New or proposed regulations require the presence of zero, or an undetectable, fluorocarbon impurities in photopatternable polyimide precursor solutions.

[0007] U.S.5,294,696 disclosed use of an acylated dihydroquinoline derivative in formation of polyisoimides. This reagent is expensive, generates carbon dioxide gas during synthesis, and is difficult to remove from the resulting polymer (i.e., yields a product composition that is difficult to purify).

[0008] U.S.5,892,061 disclosed the use of haloiminium salts, especially 2-chloro-1,3- dimethylimidazolinium chloride. The process is undesirable for electronic applications because it introduces unwanted chlorine species into the final product.

[0009] It is therefore desired to identify methods to form polyisoimide polymers where the methods avoid formation of problematic by-products and / or the need for complex and expensive purification steps. SUMMARY OF THE INVENTION

[0010] Disclosed herein is a method of forming a polyisoimide comprising reacting a dianhydride with a diamine to form a polyamic acid wherein the mole ratio of amine groups to anhydride groups is from 0.7:1 to 1:1, and reacting the polyamic acid with a sulfonyl- containing dehydrating agent and a tertiary amine base to form a polyisoimide. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Referring now to the figures, which are exemplary embodiments, and wherein the like elements are numbered alike.

[0012] Fig.1 is an FTIR spectrum for certain compositions made by the method as disclosed herein and by a comparative method. DETAILED DESCRIPTION OF THE INVENTION

[0013] The method disclosed herein reacts a polyamic acid with a dehydrating agent in the presence of a tertiary amine to produce the polyisoimide. The dehydrating agent is a sulfonyl-containing compound. This reaction forms sulfonic acid byproducts which are water soluble and can be removed by washing with water. Surprisingly, this method can producethe polyisoimide in preference to a polyimide. For example, the peak intensity ratio (ratio of maximum absorption intensity or ratio of peak heights) on Fourier Transform Infrared Spectroscopy (FTIR) of a peak indicative of polyisoimide at 1800-1803 cm-1to a peak indicative of polyimide at 1780-1783 cm-1in the reaction product can be greater than 1.1:1, greater than 1.2:1, greater than 1.3:1, greater than 1.4:1, greater than 1.5:1, greater than 1.7:1, or greater than 2:1. Desirably the amount of polyimide is minimized. In addition, this method avoids fluorinated species and acid byproducts produced are water soluble and The polyisoimideThe for example, repeat ONY1N n OX1 Ounits(1-p) or (1-m)O(1-p)(1-m) In the formula (1-p) the polyisoimide is linked in with para connectivity. In the formula (1-m) the polyisoimide is linked with meta connectivity. When referred to as formula (1) it implies the polyisoimide can be either para linked, meta linked, or a combination of both types of linkages. In the formula (1), X1is a tetravalent aromatic or alicyclic group, preferably an group, preferably an aromatic group. monomers. The polyisoimide with a in formula (2) where the capping monomer unit and the capping unit canwhere R0is a H, aliphatic hydrocarbon group having 1 to 4 carbon atoms (preferably 1 or 2) such as, for example, a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, an n-butyl group, and the like, or a group as shown in formula (3) or (4). (3) -(CH2)m-C(R5)=CR3R4 (4)

[0015] In the formula (3) and (4), R3 to R5 are independently a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and m is an integer of 1 to 10, 2 or 3. of the X1 of the formula (1) may be a a tetravalent aromatic heterocyclic group. A preferred. Examples of the tetravalent aromatic (1) include, but are not limited to, a groupw s preferable), a su ethyl)methylene group, or l ester group and X and Y a benzene ring to w ethylene group, a sulfoxide or sulfonyl group, a bis(trifluoromethyl)methylene group, or a difluoromethylene group, more preferably —O—.

[0017] The divalent aromatic group of the Y1 of the formula (1) may be a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group. A divalent aromatic hydrocarbon group is preferable. The divalent aromatic hydrocarbon group of the Y1 of the formula (1) can include, but is not limited to, a group represented by one of the following., ,aliphatic hydrocarbon group (preferably having 1 to 10 carbon atoms, more preferably having 1 to 6 carbon atoms) include a methyl group and the like. For example, R12 and R15 to R19 may be hydrogen atoms, and R13and R14may be monovalent aliphatic hydrocarbon groups. The monovalent organic group having a halogen atom (preferably a fluorine atom) can have 1 to 10 carbon atoms, preferably having 1 to 6 carbon atoms. A specific example is a trifluoromethyl group. The divalent aromatic group of the Y1 of the formula (1) may contain ether or other linkages Z where Z is an ether group (—O—), a sulfide group (—S—) (—O— is preferable), a sulfoxide group, a sulfonyl group, a methylene group, a bis(trifluoromethyl)methylene group, or a difluoromethylene group, a carbonyl-containing group or an alkyl ester group. The divalent aromatic group of the Y1containing an ether or other linkage may have meta or para linkages. The isoimidization Step

[0018] To form the polyisoimide a polyamic acid is reacted with a dehydrating agent and a tertiary amine base coreagent to produce the polyisoimide.

[0019] A generic reaction scheme of the isoimidization step transforming the polyamic acid to the polyisoimide can be shown as: where X1, Y1, and R0 are as described above. For example, the polyamic acid may be capped with an aliphatic hydrocarbon or a structure as in formula (3) or (4) or may be uncapped with R0 being H.

[0020] The dehydrating agent is a sulfonyl-containing compound. The sulfonyl- containing dehydrating agent can be, for example, a hydrocarbon-based sulfonic acid anhydride (such as methanesulfonic acid anhydride, ethane sulfonic acid anhydride, or propane sulfonic acid anhydride) or a hydrocarbon based sulfonyl chloride, such as aryl sulfonyl chlorides like toluene sulfonyl chloride or alkane sulfonyl chlorides like methanesulfonyl chloride, ethanesulfonyl chloride, propanesulfonyl chloride. The amount of the dehydrating agent can be proportional to the desired amount of polyisoimide to be formed. For example, the amount can be one equivalent of dehydrating agent per equivalent of isoimide bonds formed. For example, the amount may be one equivalent of dehydrating agent to one equivalent of amide to one carboxylic acid group (i.e.1:1:1) which can react to form the isoimide functionality. As another example, the amount of dehydrating agent may also be in an excess, for instance equivalent ratios of dehydrating agent per 1 equivalent of amide per one equivalent of carboxylic acid group can be from greater than 1:1:1 to up 1.1:1:1, up to 1.2:1:1:, or up to 1.5:1:1. For example, an excess of dehydrating agent may be desirable if there is a possibility that there is some water in the system. If it is desired to form less than a stoichiometric amount of the possible isoimide bonds in a polymer, then a lower level of dehydrating agent can be used, for instance from 0.5 equivalents or from 0.8 equivalents of dehydrating agent per equivalent of amide per equivalent of carboxylic acid group (e.g., from 0.5:1:1, or from 0.8:1:1 up to less than 1:1:1. The concentration of the dehydrating agent in the reaction mixture can be determined by the concentration of the amide and carboxylic acids to be cyclized and the desired number of equivalents of dehydrating agent.

[0021] The base coreagent facilitates the dehydration of the polyamic acid by catalyzing the reaction mechanism and acting as a base to form a salt with the acids formed during the reaction. Examples of suitable coreagents include organic tertiary amines. Examples of specific suitable organic amines include isoquinoline, quinoline, pyridine and pyridine derivatives, such as alkyl pyridines (e.g., picoline (i.e., methyl pyridine, such as 3- methyl pyridine and 5-ethyl-2-methylpyridine)), alkyoxy pyridines (e.g., methoxypyridines, such as 4-methoxy pyridine and 2,6-dimethoxy pyridine), and alkylamino pyridines (e.g., dialkyl amino pyridines (DAAPs), such as 4-dimethylaminopyridines). Other examples include aliphatic amines such as N,N-diisopropylethylamine, triethylamine, or cycloaliphatic amines, such as 1,4-Diazabicyclo[2.2.2]octane and 1,8-Diazabicyclo[5.4.0]undec-7-ene, and ethylmorpholine. A tertiary amine base, preferably from the list of pyridine, 3- methylpyridine, 2 methyl pyridine, 4-methyl pyridine, 5-ethyl-2-methyl pyridine, the isomersof lutidine, the isomers of collidine, trialkylamines, tertiary cyclohexylamines, methyl imidazololes, N,N’-dimethyl-4-aminopyridine, alkylmorpholine derivatives; and more preferably from the list of 3-methylpyridine, 5-ethyl-2-methyl pyridine, the isomers of lutidine, trialkylamines, and N,N’-dimethyl-4-aminopyridine. The amount of the base can be about 1.25 to 2 times the number of equivalents of the dehydrating reagent. The dehydrating agents produce two equivalents of acid after the polyisoimide is formed, and it is found that having about the same amount of base present to form a salt with the acid formed greatly enhances the reaction conversion. More preferably the amount of base used versus the amount of dehydrating agent is 1.5 to 2 equivalents base versus one equivalent of dehydrating agent. A maximum of 2 equivalents base to one equivalent dehydrating agent is desired when the reaction scheme occurs in a single reaction vessel (a one pot reaction where the polyisoimide will be subsequently reacted). However, if it is desired to stop the reaction after this step, the maximum equivalents of base to dehydrating agent can be higher than 2 (e.g., up to 3:1, up to 4:1 or more).

[0022] The polyisoimide formation step can be sensitive to temperature. If the temperature is too hot, the selectivity may instead favor the formation of polyimide instead of polyisoimide. The temperature of the formation step can be from -5, or from 0 up to 50, up to 40, up to 30, or up to 25℃.

[0023] The polyisoimide formation step can be sensitive to mixing and the rate and sequence of reagent additions. The formation of a salt between the acid produced during dehydration and the base can generate heat in the reaction mixture, which can result in an acceleration of the reaction but also in decomposition of the product polyisoimide to a polyimide. Therefore, the mixing and rate of addition during the reaction can be important to producing the best results. The reaction can be mixed rapidly enough to maintain an even temperature throughout the solution. For example, in a cylindrical reactor up to 100L the stir rate can be from 100 to 500 rpm. Either the dehydrating agent or the base coreagent may be added to the polyamic acid solution first. The second reagent to be added (which can be either the base coreagent or the dehydrating agent) can be added more slowly to reduce heat build-up. For example, the second reagent can be added over at least 15 minutes, or over at least 30 minutes, or over at least 60 minutes. The rate of addition can be set to maintain a desired temperature during the polyisoimide formation.

[0024] The polyisoimide formation step can be sensitive to the solubility of the salts formed and the concentration of reagents. Preferably, the solubility of the salts formed and the concentrations of the reagents and polymer combine such that the reaction is mostlyhomogenous and there are limited amounts of solids formed during the polyisoimide formation. The amount of solids generated during the polyisoimide formation step is preferably less than 10% by weight, more preferably less than 5% by weight, and most preferably less than 1% solids by weight. If too many solids are generated, there can be a poor conversion to the polyisoimide.

[0025] The polyisoimide formation reaction can occur in a solvent, preferably an aprotic solvent. Examples of such solvents include N,N-dimethylpropanamide (DMPr); N- methyl-2-pyrrolidone (NMP); dimethylacetamide (DMAc); 3-methoxy-N,N- dimethylpropanamide (KJCMP-100); dimethylformamide (DMF); dimethyl sulfoxide (DMSO); gamma-butyrolactone (BLO); propylene carbonate (PC); and tetrahydrofuran (THF). The polyamic acid

[0026] The polyamic acid that is dehydrated to the polyisoimide in the imidization step can be formed by reaction of a dianhydride with a diamine.

[0027] The dianhydride can be, for example, pyromellitic dianhydride (PMDA), 3,3’,4,4’-benzophenonetetracarboxylic dianhydride (BTDA), 3,3’,4,4’- biphenyltetracarboxylic dianhydride (BPDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 3,3’,4,4’-diphenylsulfonetetracarboxylic dianhydride (DSDA), 1,2,4,5- benzenetetracarboxylic dianhydride (BTDA), naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 4,4’- oxydiphthalic anhydride (ODPA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NDPA), 1,2,3,4-cyclohexanetetracarboxylic dianhydride (CHDA), 2,3,3’,4’-Biphenyltetracarboxylic dianhydride (HBPDA), 1,2,3,4,5,6-Hexaphthalenetetracarboxylic dianhydride (HPTDA), 1,2,3,4-Cycloheptanetetracarboxylic dianhydride (CyC7DA), 1,3,6,8-pyrenetetracarboxylic dianhydride (PTCDA), 4,4’-diphenyl ether dianhydride (DPEDA), 1,2,3,4- cyclooctanetetracarboxylic dianhydride (COTDA), 1,4,5,8-anthracyclotetracarboxylic dianhydride (ANTCDA), 4,4’-diphenylenedianhydride (DPD), 1,3-bis(3- aminophenoxy)benzene dianhydride (3-BAPBDA), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), 2,3,6,7-Naphthalenetetracarboxylic dianhydride (NTCDA), 1,2,3,4,5,6-hexaphthalenehexacarboxylic dianhydride (HHPCDA), 1,2,3,4-cyclooctene- 1,3,4,6-tetracarboxylic dianhydride (CODA), 1,3,5,7-cyclooctatetraene tetracarboxylic dianhydride (COTCDA), 4,4’-Oxybis(2,6-dimethylphthalic anhydride) (ODMDPA), 1,3,6,8- Pyrenetetracarboxylic dianhydride (PyreneDA), 1,2,3,4-Cyclohexanetetracarboxylicdianhydride (Cy6DA), p-phenylenebis(trimellitate anhydride (TMHQ), 4,4’-Bisphenol A dianhydride (BPADA), Hydroquinone diphthalic anhydride (HQDEA), 2,2’-Bis-(3,4- Dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA), Tetrahydro-1H-5,9- methanopyrano[3,4-d]oxepine-1,3,6,8(4H)-tetraone (TCA), 1,2,3,4-Butanetetracarboxylic dianhyride (BDA) or a mixture or two or more thereof.

[0028] The multi-functional amine can have the structure H2N-Y1-(NH2)n, where n is 1 or 2, preferably 1 and Y1 is as defined above. Examples of diamines that can be used include 4,4’-diaminodiphenyl ether (ODA), 4,4’-diaminodiphenylmethane (DDM), 4,4’- diaminodiphenylsulfone (DDS), 4,4’-methylenedianiline (MDA), 3,3’-diaminobenzidine diamines such p-phenylenediamine (PPD) benzene (TAPB), 1,3-Bis(3- (DMAP), 9,9’-Bis (4- -1,3,3-trimethyl-2H-inden-5-amine, bisaniline (BisP), 2,2-bis(4-(4- aminephenoxy)phenyl)propane (BAPP), 3,3’-Diaminodiphenyl sulfone (3,3’-DDS), Bis[4-(4- aminophenoxy)phenyl] Sulfone (BAPS), trans-1,4-Diaminocyclohexane (1,4-CHDA), 1,3- Bis(3-aminophenoxy) Benzene (133-APB), Isophorone diamine, 4,4’-Diaminobenzanilide (DABA), Bis(aminomethyl)norbornane; or hydroxy diamines such as 2,2-Bis(3-amino-4- hydroxyphenyl)hexafluoropropane (6FAP), 3,3’-Diamino-4,4’-dihydroxydiphenyl Sulfone (DAHPS), 3,3’-Dihydroxy-4,4’Diamino-biphenyl (HAB), or 2,2-Bis(3-amino-4- hydroxylphenyl)propane (BHAPP); or a mixture of two or more thereof.

[0029] The multi-functional amine is preferably used in an amount less than the amount of the dianhydride groups because unreacted amine groups can react with the isoimide or dehydrating agent or both in the subsequent imidization step and a branched structure could be formed. Thus, the mole ratio of amine groups from the multi-functional amine to the ratio of anhydride groups from the dianhydride is from 0.7:1, from 0.8:1 or from 0.9:1 up to 1:1.

[0030] Optionally, the dianhydride may be capped prior to formation of the polyamic acid. For example, this reaction can be represented as follows:

[0031] The capped anhydride may be produced by reaction of a dianhydride with a hydroxyl-functional molecule. The reaction can be catalyzed using a basic catalyst such as an organic base. Examples of such organic base catalyst include organic amines such as pyridine, 3-picoline, 1,4-Diazabicyclo[2.2.2]octane, 4-Dimethylaminopyridine, 5-Ethyl-2- methylpyridine, 1,8-Diazabicyclo(5.4.0)undec-7-ene, 1,5-Diazabicyclo(4.3.0)non-5-ene, diisopropylethylamine amine, or triethyl amine.

[0032] The capping reaction can occur in a solvent, preferably an aprotic solvent. Examples of such solvents include N,N-dimethylpropanamide (DMPr); N-methyl-2- pyrrolidone (NMP); dimethylacetamide (DMAc); 3-methoxy-N,N-dimethylpropanamide (KJCMP-100); dimethylformamide (DMF); dimethyl sulfoxide (DMSO); gamma- butyrolactone (BLO); propylene carbonate (PC); and tetrahydrofuran (THF).

[0033] The mole ratio of dianhydride to hydroxy-functional molecule (e.g., the hydroxyalkyl (meth)acrylate or the ethylenically unsaturated alcohol) can be adjusted to provide the degree of capping of the dianhydride desired. The ethylenic unsaturated groups on the esterified dianhydride will provide photoactivity for the resulting polyimide precursor product and will also control molecular weight of the polymer during synthesis. For example, the dianhydride and the hydroxy-functional molecule can be provided at a mole ratio of from 1:0.4 to 1:0.02.

[0034] The concentration of the dianhydride in the solvent can be, for example, from 0.1, from 0.15, or from 0.2 moles / liter up to 0.5, up to 0.4, or up to 0.3 moles / liter. The concentration of the hydroxyl-functional monomer (e.g., the hydroxyalkyl (meth)acrylate or the ethylenically unsaturated alcohol) in the solvent during capping can be, for example, from 0.002, from 0.02 up to 0.2, or up to 0.3, moles / liter.

[0035] The amount of basic catalyst used can be, for example, in a mole ratio of catalyst to dianhydride of at least 0.001:1, or at least 0.01:1 up to 0.4:1, or up to 0.2:1.

[0036] The reaction of the dianhydride with the hydroxyalkyl (meth)acrylate can occur at a temperature of, for example 10 to 100℃ or 15 to 50℃. The reaction can be run at room temperature. The time for the reaction can be, for example, from 10, from 20 or from 30 minutes, or from 1 hour up to 5, up to 4, or up to 3 hours. At room temperature, for be from 1 hour to 3 hours.functional molecule can include ethylenic unsaturation to enable later photopolymerization of the polyimide precursor. For example, the hydroxyl-functional molecule can be an ethylenically unsaturated alcohol having at least 3 carbon atoms,preferably up to no more than 8, up to 7, up to 6, or up to 5 carbon atoms. As another example, the hydroxyl-functional molecule can be a hydroxyalkyl (meth)acrylate.

[0038] A “(meth)acrylate” as used herein encompasses, acrylates, methacrylates, and mixtures carbonprimary alcohol, such as, for example, CH2=CZ1-C(O)-O-(CH2)n-OH where n is an integer of at least 1 and preferably 2 to 5, more preferably 2 to 3 carbon atoms. Specific examples of such primary alcohols include hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate, and hydroxybutyl acrylate. Alternatively, hydroxyalkyl (meth)acrylate can be a secondary alcohol, such as, for example, the CH2=CZ1-C(O)-O-Y1(OH)-O-(O)C-CZ2=CH2, where Z1 and Z2 are H or CH3. Specific examples of a secondary alcohol include glycerol dimethacrylate, 3-(acryloyloxy)-2-hydroxypropyl methacrylate . Examples of ethylenically unsaturated alcohols include allyl alcohol, 3-buten-1-ol, and 4- penten-1-ol.

[0040] The reaction of the dianhydride, an end-capped dianhydride (which is optional but preferred), and the diamine to form a polyamic acid can be represented as follows: where X1 and Y1 and R0 are as described herein. The reaction can be conducted in the same solvent as the (optional but preferred) capping reaction. The polyamic acid formation reaction can be in the same vessel and carried out directly after the optional capping reaction.

[0041] The polyamic acid formation reaction can occur in a solvent, preferably an aprotic solvent. Examples of such solvents include N,N-dimethylpropanamide (DMPr); N- methyl-2-pyrrolidone (NMP); dimethylacetamide (DMAc); 3-methoxy-N,N- dimethylpropanamide (KJCMP-100); dimethylformamide (DMF); dimethyl sulfoxide(DMSO); gamma-butyrolactone (BLO); propylene carbonate (PC); and tetrahydrofuran (THF).

[0042] The mole ratio of the dianhydride, capped anhydride, and diamine helps determine the MW of the resulting polyamic acid. In order to prevent interference with further chemistry, the diamine monomer is generally used in a sub-stoichiometric amount. This reduces the presence of unreacted amine groups to low levels. The mole ratio of amine groups to anhydride groups can be from 0.7:1 to 1:1.

[0043] The reaction can be catalyzed using a basic catalyst such as a tertiary amine base. Examples of such organic base catalyst include organic amines such as pyridine, 3- picoline, 1,4-Diazabicyclo[2.2.2]octane, 4-Dimethylaminopyridine, 5-Ethyl-2- methylpyridine, 1,8-Diazabicyclo(5.4.0)undec-7-ene, 1,5-Diazabicyclo(4.3.0)non-5-ene, for toin the solvent can be, for example, from 0.05, from 0.1, from 0.15, or from 0.2 moles / liter up to 0.5, up to 0.4, or up to 0.3 moles / liter. The concentrations of the diamine will be determined by the overall equivalents used in the polyamic acid formation reaction.

[0045] The reaction of the dianhydride and capped anhydride with the diamine can occur at a temperature of, for example from 10, from 15, from 20 or from 25℃ up to 100 or up to 50℃. The time for the reaction can be, for example, from 30 minutes, or from 1 hour up to 6, up to 5, or up to 4 hours. At 35oC temperature, for example, the reaction time can be from 2 hour to 4 hours. Esterification of the polyisoimide

[0046] The polyisoimide may be further reacted with a hydroxy compound to form a polyamic acid ester. The addition of the hydroxy functional compound allows for the addition of desired functional groups such as photochemically active groups (e.g., groups having ethylenic unsaturation) via the formed ester. This occurs by opening of the polyisoimide ring with the hydroxy group. The general reaction is as follows:where R0, X1, and Y1, are as described herein. The hydroxyl functional compound can provide an R0that is the same or different from the R0used in providing a capped polyamic acid (or capped dianhydride). The reaction can be conducted in the same solvent as the polyisoimide formation reaction. The optional anhydride capping reaction, polyamic acid formation, polyisoimide formation, and polyamic acid ester formation reaction can be in the same vessel and carried out as a one pot reaction sequence.

[0047] The polyisoimide esterification reaction can occur in a solvent, preferably an aprotic solvent. Examples of such solvents include N,N-dimethylpropanamide (DMPr); N- methyl-2-pyrrolidone (NMP); dimethylacetamide (DMAc); 3-methoxy-N,N- dimethylpropanamide (KJCMP-100); dimethylformamide (DMF); dimethyl sulfoxide (DMSO); gamma-butyrolactone (BLO); propylene carbonate (PC); and tetrahydrofuran (THF).

[0048] The mole ratio of the added hydroxy compound can be one equivalent or more of the amount of polyisoimide present (e.g.1:1 up to 5:1 or up to 4:1). Excess hydroxy compound can be used to accelerate the esterification reaction. The concentrations of the hydroxy compound will be determined by the overall equivalents of polyisoimide that are to be reacted.

[0049] The reaction can be optionally catalyzed using a basic catalyst such as a tertiary amine base. Examples of such organic base catalyst include organic amines such as pyridine, 3-picoline, 1,4-Diazabicyclo[2.2.2]octane, 4-Dimethylaminopyridine, 5-Ethyl-2- methylpyridine, 1,8-Diazabicyclo(5.4.0)undec-7-ene, 1,5-Diazabicyclo(4.3.0)non-5-ene, diisopropylethylamine amine, or triethyl amine. The catalyst may be remaining from prior reactions in the case of single pot processes.

[0050] The esterification reaction can occur at a temperature of, for example from 10. from 15, from 20 or from 25℃ up to 100 or up to 50℃. The time for the reaction can be, for example, from 30 minutes, from 1 hour, from 2 hours, from 3 hours or from 4 hours up to 24 or up to 20 hours. At 45℃ temperature, for example, the reaction time can be from 4 hour to 20 hours. The use of higher reaction temperatures can result in the decomposition of some of the photoactive groups present in the polymer chain.

[0051] The polyisoimide or the polyamic acid ester can be separated from the reaction mixture, for example by precipitation and filtration. Additional wash with water, solvent, or a combination thereof can be used to remove any impurities such as residual sulfonic acids. Due to the advantageous solubility of sulfonic acids in water versus ureas (comparing to priorart using carbodiimides), the level of sulfonic acids can be reduced below 5000 ppm, more preferably below 2500 ppm.

[0052] The polyisoimide or the polyamic acid ester can have a weight average molecular weight, for example, of at least 10,000, at least 15,000, or at least 20,000 grams per mole up to 130,000, up to 100,000, or up to 80,000 grams per mole as determined by gel permeation chromatography (GPC) using a polystyrene standard. The polyisoimide or the polyamic acid ester preferably has a polydispersity (weight average molecular weight / number average molecular weight) of less than 3, of no greater than 2.5, or of no greater than 2.0.

[0053] The polyamic acid ester can have amount of esterification with ethylenically unsaturated hydroxyl-functional monomers, of, for example, is at least 50%, preferably 70 to 90% based on total number of acid and ester groups. This can be measured for example using 1H NMR proton integration the characteristic vinyl proton peaks on the esters and the characteristic peaks of protons on dianhydrides or diamines or both. EXAMPLES Method of determining amount of polyisoimide

[0054] An FTIR spectrum obtained of the product after the isoimidization step can be used to determine the amount of polyisoimide formed relative to any amount of polyimide form. The FTIR spectrum can be obtained by isolating the polymer from the reaction mixtures by precipitating the reaction mix into isopropanol. The precipitated solids are filtered and then washed in the funnel 1 more time with isopropanol. A final rinse of the solids with IPA is done in the filter funnel and then the solids are dried by sucking air thru the funnel. The solids are then analyzed using a Perkin Elmer (SpectrumOne) ATR-FTIR system. An example FTIR with the peak identification is shown in Error! Reference source not found.. Isoimide provides a peak at 1802 cm-1while an imide provides a peak at 1781 cm-1. A ratio of the peak intensities can allow one to make an estimate of mole ratio. A value of 0 absorbance is assigned when no isoimide peak is visible in the spectra to set a spectra baseline. In cases where the isoimide stretch is strong it can obscure the imide peak, so the absorbance of the spectra at 1781 cm-1is recorded. An artifact of this measurement method is that some amount of imide will be ‘measured’ even when very little or no imide is present, unless the isoimide peak is exceptionally sharp. Example 1 – Preparation of polyamic acid, PAA1

[0055] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 14.5 grams of diamine, 24.8 grams of Dianhydride, 0.135 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 2.9 grams of 2-hydroxyethyl methacrylate were combined to preparea polyamic acid, PAA1, for further testing. The batches of PAA1 used for subsequent examples had polymer Mw values of from 15k to 35k. The resulting PAA1 polymers made in solvent were stored (without isolation) and used subsequently for testing of the polyisoimide formation reaction.The PAA1 polymers were dissolved at levels between 10-12% in the dimethylpropionamide or N-methyl pyrrolidone solvent. Example 2 – Testing of various reagents for the formation of polyisoimides

[0056] In each test, the molality of the difunctional acid anhydrides (DAAs) used to make the polyamic acid polymers was calculated based on the preparation of the polyamic acid used for the test. For each molar amount of DAA it is possible to prepare two molar amounts of isoimide moieties, minus any molar amounts of anhydride groups that have reacted with a ‘capper.’ The testing employed various stoichiometries of the inventive and comparative reagents relative to the molality of the DAAs. Results are tabulated in Table 1 with the key aspects being the amount of reagent as indicated in the table by molalities of the reagents, the temperature of the reaction, the solvent, and the resulting PII / PI ratio by FTIR, where the polyamic acid was PAA1.

[0057] The PAA was prepared ahead of time in a suitable solvent and stored at 4℃. The reaction vessels were 40 mL vials with magnetic stir bars and jacketed with a custom reactor block. In most cases, the PAA solution was added to the reaction vessel first. In cases of solid dehydrating reagents, the dehydrating agent was weighed into the vial first, followed by the PAA solution. The vials were then sealed with septa and inerted with nitrogen atmosphere. Subsequent additions all occurred by syringe under a positive nitrogen pressure in the vials. In cases of liquid or pre-dissolved dehydrating agents, they were then added by syringe at the temperature specified in the table. The solutions were allowed to stir for 10 minutes and return to the temperature setpoint before the base coreagents were added. The base coreagents were added over the course of several minutes, by syringe, to maintain the desired temperature as much as possible. The reaction was then stirred for the amount of time indicated in the table, at which point a sample was withdrawn from the reactor by syringe.

[0058] Reaction samples were quenched by precipitating the reaction mix into isopropanol. The precipitated solids were filtered and then washed in the funnel once with isopropanol. A final rinse of the solids with isopropanol is done in the filter funnel and then the solids are dried by sucking air thru the funnel. The solids are then analyzed using a Perkin Elmer (SpectrumOne) ATR-FTIR system.Table 1 Sample Concentration Dehydrating Concentration Base Concentration Solvent Temperature Reaction Peak Peak PII / PI DAA (molal) agent Dehydrating coreagent Base (℃) Time intensity intensity ratio agent (molal) coreagent or for (molal) isoimide Imide C m021 A ti A h d id 039 T i th l i 039 NMP10 1 0.050 0.039 1.281 0.054 0.044 1.23 10.055 0.044 1.252 0.059 0.054 1.092 0.061 0.057 1.07 20.065 0.056 1.162 0 0.040 0o 25 2hr@150.016 0.054 0.30 2hr@25 20 0.063 02 0.0674 0.0468 1.44 20.0872 0.0601.45 20.084 0.0591.42 20.0788 0.05551.42 20.0681 0.05081.340.21 Methanesulfonyl 0.39 3-picoline 0.5 DMPR 10 2 0.0998 0.0651 chloride 1.53 0.14 p-0.23 3-picoline 0.23 DMPR10 2 0.0436 0.0380Toluenesulfonyl hl id 1.15 20.055 0.0421.31 20.0566 0.04421.28 20.0522 0.04161.25 20.0599 0.04471.34 20.0513 0.04311.19 20.0634 0.03861.64 20.0847 0.05151.64 30.0585 0.03751.56 30.152 0.08441.80 30.153 0.0771.99 2 0.046 0.027 1.70 2 0.109 0.057 1.91 20.118 0.0601.97 30.0285 0.02121.340.20 Methanesulfonyl 0.37 Triethylamine 0.75 DMPR 10 3 0.133 0.0595 Chloride 2.24 0.20 Methanesulfonyl 0.37 N,N’-dimethyl-0.75 DMPR10 1 0.140 0.0661Chloride cyclo h l i 2.12 20.110 0.0591.86 20.172 0.0862.00 1 0.018 0.008 2.25 2 0.039 0.017 2.29 1 0.044 0.021 2.10 20.134 0.073 1.83Example 3 – Formation of polyamic acid ester from PII

[0059] Some of the polyisoimides formed in Example 2 were reacted with an alcohol to create polyamic acid esters. Example 3.13 corresponds to the reaction of the polyisoimide composition from sample 13 with the alcohol, Example 3.14 refers to the reaction using sample 14, and so on. The polyisoimide examples were reacted with 2-hydroxyethyl methacrylate (HEMA). Each polyisoimide was reacted with 2 equivalents of HEMA relative to the dianhydride concentration. The HEMA was added to the reaction at the temperature of the polyisoimide hold, usually 10℃. The reaction was then heated to 45℃ and held for 18 hours. The resulting reaction solution was precipitated into an excess of water, causing the polyamic acid ester to precipitate. The polymer product was then washed several times with water and dried in a vacuum oven at 45℃ overnight. The water washing of the polymer resin removes most of the unreacted HEMA, although a trace amount of unreacted HEMA may remain in the resin. About 80 mg of the dried polymer was dissolved in deuterated dimethyl sulfoxide and a proton NMR was taken to measure the ratio of backbone aryl hydrogens in the polymer chain versus alkenyl protons in the incorporated 2-hydroxymethyl methacrylate. The table below shows the results. For the starting PAA1 composition, if the polymer had an infinite MW, the maximum number of alkenyl protons versus aryl protons would be 0.333, or 1 versus 3. Sample Concentration Concentration Integral of Integral of # of Alkenyl DAA ( l l) HEMA arylExample 4

[0060] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 26.74 grams of 2,2’-Dimethyl [1,1’-biphenyl] -4,4’diamine, 0.72 grams p-phenylene diamine, 29.20 grams of 4,4’-Oxydiphthalic Anhydride, 18.46 grams of 1,1'-Biphenyl-3,3',4,4'-tetracarboxylic dianhydride, 0.261 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 6.14 grams of 2-hydroxyethyl methacrylate were combined to prepare polyamic acids PAA2. Then without isolation, PAA2 was reacted with 51.36 g methanesulfonic acid anhydride (MSAA), 66.52 g 5-Ethyl-2methylpyridine (EMP), and an excess of 2-hydroxyethyl methacrylate (57.22 g) along with additional solvent to adjust PAA solids to 9-12%. The resulting Polyamic ester (PAE2) had Mw values of 41.2k and, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.265. Example 5

[0061] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 23.90 grams of 2,2’-Dimethyl [1,1’-biphenyl] -4,4’diamine, 7.51 grams of 4,4’-Oxydiphthalic Anhydride, 21.13 grams of PMDA (Pyromellitic dianhydride), 0.199 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 2.17 grams of 2-hydroxyethyl methacrylate were combined to prepare polyamic acid PAA3. Then without isolation, PAA3 was reacted with 39.66 g MSAA, 51.36 g EMP, and an excess of 2-hydroxyethyl methacrylate (44.12 g) along with additional solvent to adjust PAA solids to 8-18%. The resulting Polyamic ester (PAE3) had Mw values of 85.1k, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.267. Example 6

[0062] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 28.83 grams of 2,2’-Dimethyl [1,1’-biphenyl] -4,4’diamine, 0.77 grams p-phenylene diamine, 28.59 grams of 4,4’-Oxydiphthalic Anhydride, 18.21 grams of 1,1'-Biphenyl-3,3',4,4'-tetracarboxylic dianhydride, 0.264 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 2.75 grams of 2-hydroxyethyl methacrylate were combined to prepare polyamic acid PAA4. Then without isolation, PAA4 was reacted with 50.29 g MSAA, 65.18 g EMP, and an excess of 2- hydroxyethyl methacrylate (56.01 g) along with additional solvent to adjust PAA solids to 9- 12%. The resulting Polyamic ester (PAE4) had Mw values of from 80.8k, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.243. Example 7

[0063] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 23.18 grams of 2,2’-Dimethyl [1,1’-biphenyl] -4,4’diamine, 5.07 grams p-phenylene diamine, 31.23 grams of 4,4’-Oxydiphthalic Anhydride, 19.75 grams of 1,1'-Biphenyl-3,3',4,4'-tetracarboxylicdianhydride, 0.285 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 3.06 grams of 2-hydroxyethyl methacrylate were combined to prepare polyamic acid PAA5. Then without isolation, PAA5 was reacted with 54.93 g MSAA, 71.16 g EMP, and an excess of 2- hydroxyethyl methacrylate (61.16 g) along with additional solvent to adjust PAA solids to 9- 12%. The resulting Polyamic ester (PAE5) had Mw values of from 86.5k, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.232. Example 8

[0064] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 20.07 grams of 4,4’-Oxydianiline (ODA), 23.97 grams of PMDA (Pyromellitic dianhydride), 0.192 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 2.51 grams of 2-hydroxyethyl methacrylate were combined to prepare polyamic acid PAA6. Then without isolation, PAA6 was reacted with 36.08 g MSAA, 46.65 g EMP, and an excess of 2-hydroxyethyl methacrylate (40.10 g) along with additional solvent to adjust PAA solids to 8-10%. The resulting Polyamic ester (PAE6) had Mw values of from 61.8k, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.188. Example 9

[0065] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 40.85 grams of p-phenylenebis (trimellitate anhydride), 27.93 grams of 4,4'-[1,4-Phenylenebis(1-Methyl- ethylidene)]Bisaniline, 0.160 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 2.33 grams of 2-hydroxyethyl methacrylate were combined to prepare polyamic acid PAA7. Then without isolation, PAA7 was reacted with 29.32 g MSAA, 37.78 g EMP, and an excess of 2-hydroxyethyl methacrylate (32.51 g) along with additional solvent to adjust PAA solids to 8-10%. The resulting Polyamic ester (PAE7) had Mw values of from 95.7.5k, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.095. Example 10

[0066] Using dimethylpropionamide or N-methyl pyrrolidone as solvent, 10.27 grams p-phenylene diamine, 30.72 grams of 1,1'-Biphenyl-3,3',4,4'-tetracarboxylic dianhydride, 0.183 grams of 1,4-Diazobicyclo [2.2.2] Octane Triethylenediamine, and 2.66 grams of 2- hydroxyethyl methacrylate were combined to prepare polyamic acid PAA8. Then without isolation, PAA8 was reacted with 50.29 g MSAA, 65.18 g EMP, and an excess of 2- hydroxyethyl methacrylate (56.01 g) along with additional solvent to adjust PAA solids to 8- 10%. The resulting Polyamic ester (PAE8) had Mw values of from 74.7k, and 1H NMR indicated # of Alkenyl protons / aryl proton was 0.260.

[0067] This disclosure further encompasses the following aspects.

[0068] Aspect 1: A method comprising reacting a dianhydride with a diamine to form a polyamic acid wherein the mole ratio of amine groups to anhydride groups is from 0.7:1 to 1:1, and reacting the polyamic acid with a sulfonyl-containing dehydrating agent and a tertiary amine base to form a polyisoimide.

[0069] Aspect 2: The method of Aspect 1 wherein the sulfonyl-containing dehydrating agent comprises a hydrocarbon-based sulfonic acid anhydride, preferably, methanesulfonic acid anhydride, ethane sulfonic acid anhydride, or propane sulfonic acid anhydride, or a hydrocarbon based sulfonyl chloride, preferably as aryl sulfonyl chlorides or alkane sulfonyl chlorides, more preferably toluene sulfonyl chloride, methanesulfonyl chloride, ethanesulfonyl chloride, or propanesulfonyl chloride.

[0070] Aspect 3: The method of Aspect 1 or 2 wherein the tertiary amine base comprises pyridine, 3-methylpyridine, 2 methyl pyridine, 4-methyl pyridine, 5-ethyl-2- methyl pyridine, the isomers of lutidine, the isomers of collidine, trialkylamines, tertiary cyclohexylamines, methyl imidazololes, N,N’-dimethyl-4-aminopyridine, or alkylmorpholine derivatives; preferably 3-methylpyridine, 5-ethyl-2-methyl pyridine, the isomers of lutidine, trialkylamines, or N,N’-dimethyl-4-aminopyridine.

[0071] Aspect 4: The method of any one of the preceding Aspects wherein a Fourier transfer infrared spectroscopy of the reaction product shows a peak intensity ratio of peak height at 1800-1803 cm-1to a peak height at 1780-1783 cm-1in the reaction product is at least 1.3:1, preferably at least 1.5:1, more preferably at least 1.8:1.

[0072] Aspect 5: The method of any one of the previous Aspects wherein the dianhydride comprises pyromellitic dianhydride (PMDA), 3,3',4,4'- benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 3,3',4,4'- diphenylsulfonetetracarboxylic dianhydride (DSDA), 1,2,4,5-benzenetetracarboxylic dianhydride (BTDA), naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTDA), 1,2,3,4- cyclopentanetetracarboxylic dianhydride (CPDA), 4,4'-oxydiphthalic anhydride (ODPA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NDPA), 1,2,3,4-cyclohexanetetracarboxylic dianhydride (CHDA), 2,3,3',4'-Biphenyltetracarboxylic dianhydride (HBPDA), 1,2,3,4,5,6- Hexaphthalenetetracarboxylic dianhydride (HPTDA), 1,2,3,4-Cycloheptanetetracarboxylic dianhydride (CyC7DA), 1,3,6,8-pyrenetetracarboxylic dianhydride (PTCDA), 4,4'-diphenyl ether dianhydride (DPEDA), 1,2,3,4-cyclooctanetetracarboxylic dianhydride (COTDA), 1,4,5,8-anthracyclotetracarboxylic dianhydride (ANTCDA), 4,4'-diphenylenedianhydride (DPD), 1,3-bis(3-aminophenoxy)benzene dianhydride (3-BAPBDA), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), 2,3,6,7-Naphthalenetetracarboxylic dianhydride (NTCDA), 1,2,3,4,5,6-hexaphthalenehexacarboxylic dianhydride (HHPCDA), 1,2,3,4-cyclooctene-1,3,4,6-tetracarboxylic dianhydride (CODA), 1,3,5,7-cyclooctatetraene tetracarboxylic dianhydride (COTCDA), 4,4'-Oxybis(2,6-dimethylphthalic anhydride) (ODMDPA), 1,3,6,8-Pyrenetetracarboxylic dianhydride (PyreneDA), 1,2,3,4- Cyclohexanetetracarboxylic dianhydride (Cy6DA), p-phenylenebis(trimellitate anhydride (TMHQ), 4,4'-Bisphenol A dianhydride (BPADA), Hydroquinone diphthalic anhydride (HQDEA), 2,2'-Bis-(3,4-Dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA), Tetrahydro-1H-5,9-methanopyrano[3,4-d]oxepine-1,3,6,8(4H)-tetraone (TCA), 1,2,3,4- Butanetetracarboxylic dianhyride (BDA), or a mixture or two or more thereof

[0073] Aspect 6: The method of any one of the previous Aspects wherein the diamine comprises 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (DDM), 4,4'- diaminodiphenylsulfone (DDS), 4,4'-methylenedianiline (MDA), 3,3'-diaminobenzidine (DAB), 4,4'-diaminostilbene (DAS), a phenylenediamine, such as p-phenylenediamine (PPD) or m-pheneylene diamine (MPD), 1,3,5-Tris(aminophenoxy)benzene (TAPB), 1,3-Bis(3- aminophenoxy)benzene (3,3'-BAPB), 2,2’-Dimethylbenzidine) (DMAP), 9,9'-Bis (4- aminophenyl) fluorene (FDA), 1-(4-Aminophenyl)-1,3,3-trimethyl-2H-inden-5-amine (PIDA), diamine (4,4′-(1,4-Phenylenediisopropylidene)bisaniline (BisP), 2,2-bis(4-(4- aminephenoxy)phenyl)propane (BAPP), 3,3'-Diaminodiphenyl sulfone (3,3’-DDS), Bis[4-(4- aminophenoxy)phenyl] Sulfone (BAPS), trans-1,4-Diaminocyclohexane (1,4-CHDA), 1,3- Bis(3-aminophenoxy) Benzene (133-APB), Isophorone diamine, 4,4’-Diaminobenzanilide (DABA), Bis(aminomethyl)norbornane, 2,2-Bis(3-amino-4- hydroxyphenyl)hexafluoropropane (6FAP), 3,3'-Diamino-4,4'-dihydroxydiphenyl Sulfone (DAHPS), 3,3’-Dihydroxy-4,4’Diamino-biphenyl (HAB), 2,2-Bis(3-amino-4- hydroxylphenyl)propane (BHAPP); or a mixture of two or more thereof.

[0074] Aspect 7: The method of any one of the previous Aspects further comprising reacting the polyisoimide with a compound of formula ROH to esterify the polyisoimide to a polyamic acid ester comprising R groups.

[0075] Aspect 8: The method of Aspect 7 wherein the ROH is hydroxyalkyl (meth)acrylate or an ethylenically unsaturated alcohol, preferably a hydroxyalkyl (meth)acrylate.

[0076] Aspect 9: The method of Aspect 8 wherein the ROH comprises the hydroxyalkyl (meth)acrylate comprises hydroxyethyl methacrylate, hydroxyethyl acrylate,hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, allyl alcohol, 3-butene-1-ol, or 4-pentene-1-ol.

[0077] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt.%, or, more specifically, 5 wt.% to 20 wt.%”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt.% to 25 wt.%,” etc.). Moreover, stated upper and lower limits can be combined to form ranges (e.g., “at least 1 or at least 2 weight percent” and “up to 10 or 5 weight percent” can be combined as the ranges “1 to 10 weight percent”, or “1 to 5 weight percent” or “2 to 10 weight percent” or “2 to 5 weight percent”).

[0078] The disclosure may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The disclosure may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and / or objectives of the present disclosure.

[0079] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0080] Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

Claims

What is claimed is:

1. A method comprising (a) reacting a dianhydride with a diamine to form a polyamic acid wherein the mole ratio of amine groups to anhydride groups is from 0.7:1 to 1:1, (b) reacting the polyamic acid with a sulfonyl-containing dehydrating agent and a tertiary amine base to form a reaction product comprising polyisoimide.

2. The method of claim 1 wherein a Fourier transfer infrared spectroscopy of the reaction product shows a peak intensity ratio of peak height at 1800-1803 cm-1to a peak height at 1780-1783 cm-1in the reaction product is at least 1.3:1, preferably at least 1.5:1, more preferably at least 1.8:

1.

3. The method of claim 1 or 2 wherein the sulfonyl-containing dehydrating agent comprises a hydrocarbon-based sulfonic acid anhydride, preferably, methanesulfonic acid anhydride, ethane sulfonic acid anhydride, or propane sulfonic acid anhydride, or a hydrocarbon based sulfonyl chloride, preferably as aryl sulfonyl chlorides or alkane sulfonyl chlorides, more preferably toluene sulfonyl chloride, methanesulfonyl chloride, ethanesulfonyl chloride, or propanesulfonyl chloride.

4. The method of claim 1 or 2 wherein the tertiary amine base comprises pyridine, 3- methylpyridine, 2 methyl pyridine, 4-methyl pyridine, 5-ethyl-2-methyl pyridine, the isomers of lutidine, the isomers of collidine, trialkylamines, tertiary cyclohexylamines, methyl imidazololes, N,N’-dimethyl-4-aminopyridine, or alkylmorpholine derivatives; preferably 3-methylpyridine, 5-ethyl-2-methyl pyridine, the isomers of lutidine, trialkylamines, or N,N’-dimethyl-4- aminopyridine.

5. The method of claim 1 or 2 wherein the dianhydride comprises pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'- biphenyltetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,2,4,5- benzenetetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,3,4- cyclohexanetetracarboxylic dianhydride, 2,3,3',4'-Biphenyltetracarboxylic dianhydride, 1,2,3,4,5,6-Hexaphthalenetetracarboxylic dianhydride, 1,2,3,4- cycloheptanetetracarboxylic dianhydride, 1,3,6,8-pyrenetetracarboxylicdianhydride, 4,4'-diphenyl ether dianhydride, 1,2,3,4-cyclooctanetetracarboxylic dianhydride, 1,4,5,8-anthracyclotetracarboxylic dianhydride, 4,4'- diphenylenedianhydride, 1,3-bis(3-aminophenoxy)benzene dianhydride, 3,4,9,10- perylenetetracarboxylic dianhydride, 2,3,6,7-Naphthalenetetracarboxylic dianhydride, 1,2,3,4,5,6-hexaphthalenehexacarboxylic dianhydride, 1,2,3,4- cyclooctene-1,3,4,6-tetracarboxylic dianhydride, 1,3,5,7-cyclooctatetraene tetracarboxylic dianhydride, 4,4'-dxybis(2,6-dimethylphthalic anhydride), 1,3,6,8- Pyrenetetracarboxylic dianhydride, 1,2,3,4-fyclohexanetetracarboxylic dianhydride, p-phenylenebis(trimellitate anhydride, 4,4'-bisphenol A dianhydride, Hydroquinone diphthalic anhydride, 2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride, tetrahydro-1H-5,9-methanopyrano[3,4- d]oxepine-1,3,6,8(4H)-tetraone, 1,2,3,4-futanetetracarboxylic dianhyride, or a mixture or two or more thereof.

6. The method of claim 1 or 2 wherein the diamine comprises 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'- methylenedianiline, 3,3'-diaminobenzidine, 4,4'-diaminostilbene, phenylenediamine, 1,3,5-tris(aminophenoxy)benzene, 1,3-bis(3- aminophenoxy)benzene, 2,2’-imethylbenzidine, 9,9'-fis (4-aminophenyl) fluorene, 1-(4-aminophenyl)-1,3,3-trimethyl-2H-inden-5-amine, diamine (4,4′-(1,4- Phenylenediisopropylidene)bisaniline, 2,2-bis(4-(4- aminephenoxy)phenyl)propane, 3,3'-aiaminodiphenyl sulfone, bis[4-(4- aminophenoxy)phenyl] sulfone, trans-1,4-diaminocyclohexane, 1,3-bis(3- aminophenoxy) benzene, isophorone diamine, 4,4’-diaminobenzanilide, bis(aminomethyl)norbornane, 2,2-bis(3-amino-4- hydroxyphenyl)hexafluoropropane, 3,3'-diamino-4,4'-dihydroxydiphenyl Sulfone, 3,3’-dihydroxy-4,4’-diamino-biphenyl, 2,2-bis(3-amino-4- hydroxylphenyl)propane; or a mixture of two or more thereof.

7. The method of claim 1 or 2 further comprising reacting the polyisoimide with a compound of formula ROH to esterify the polyisoimide to a polyamic acid ester comprising R groups.

8. The method of claim 7 wherein the ROH is hydroxyalkyl (meth)acrylate or an ethylenically unsaturated alcohol, preferably a hydroxyalkyl (meth)acrylate.

9. The method of claim 8 wherein the ROH comprises the hydroxyalkyl (meth)acrylate comprises hydroxyethyl methacrylate, hydroxyethyl acrylate,hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, allyl alcohol, 3-butene-1-ol, or 4-pentene-1-ol.

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