Anisotropic copoly(imide oxetane) coatings and articles of manufacture, copoly(imide oxetane)s containing pendant fluorocarbon moieties, oligomers and processes therefor

Abstract

Copoly(imide oxetane) materials are disclosed that can exhibit a low surface energy while possessing the mechanical, thermal, chemical and optical properties associated with polyimides. The copoly(imide oxetane)s are prepared using a minor amount of fluorinated oxetane-derived oligomer with sufficient fluorine-containing segments of the copoly(imide oxetane)s migrate to the exterior surface of the polymeric material to yield low surface energies. Thus the coatings and articles of manufacture made with the copoly(imide oxetane)s of this invention are characterized as having an anisotropic fluorine composition. The low surface energies can be achieved with very low content of fluorinated oxetane-derived oligomer. The copolymers of this invention can enhance the viability of polyimides for many applications and may be acceptable where homopolyimide materials have been unacceptable.

Claims

1. A copoly(amic acid oxetane) having the structure represented by:
—(G—A)—(D—A)— wherein: G is represented by the formula
—NH—R.sup.1—C(O)—O—J—C(O)—R.sup.1—HN— wherein: J is [CH.sub.2—CR.sup.2R.sup.3—CH.sub.2—O].sub.m or [(CH.sub.2—CR.sup.2R.sup.3—CH.sub.2—O).sub.p—(R.sup.6—O).sub.q—(CH.sub.2—CR.sup.2R.sup.3—CH.sub.2—O).sub.r] wherein R.sup.6 is a substituted or unsubstituted aliphatic or aromatic moiety of 2 to 16 carbons; R.sup.1 is an aliphatic or aromatic hydrocarbon moiety of 1 to 10 carbon atoms; R.sup.2 is —H, —F, or an alkyl of 1 to 6 carbon atoms; R.sup.3 is —F, —R.sup.4H.sub.(n-a)F.sub.a, —R.sup.5—O—R.sup.4H.sub.(n-a)F.sub.a, or —O—R.sup.4H.sub.(n-a)F.sub.a, wherein R.sup.4 is an alkyl or ether moiety of 1 to 30 carbons, R.sup.5 is an alkyl moiety of 1 to 30 carbons, a is an integer of 3 to n, and n is twice the number of carbon atoms in the alkyl moiety plus 1; m is between about 4 and 500, p is between about 4 and 150, q is between about 1 and 150; and r is an integar; A is represented by the formula wherein: ##STR00003## L is a hydrocarbyl-containing moiety of 2 to 100 carbon atoms, optionally containing divalent radicals selected from the group consisting of oxygen, silyl, sulfur, carbonyl, sulfonyl, phosphonyl, perfluoro, tertiary amino, and imido; D is represented by the formula
—NH—Z—NH— wherein: Z is a hydrocarbyl-containing moiety of 1 to 100 carbon atoms optionally containing divalent radicals selected from the group consisting of oxygen, sulfur, silyl, carbonyl, sulfonyl, phosphonyl, perfluoro, tertiary amino, and imido.

2. A polymer composite comprising a copolymer containing the copoly(amic acid oxetane) of claim 1 and a particulate filler, wherein the polymer composite has a water contact angle of at least 100° .

3. A process for making a copoly(amic acid oxetane) of claim 1 comprising: a. reacting an oxetane oligomer of the formula
H—O—J—H wherein J is [CH.sub.2—CR.sup.2R.sup.3—CH.sub.2—O].sub.m or [(CH.sub.2—CR.sup.2R.sup.3—CH.sub.2—O).sub.p—(R.sup.6—O).sub.q—(CH.sub.2—CR.sup.2R.sup.3—CH.sub.2—O).sub.r], wherein R.sup.6 is a substituted or unsubstituted aliphatic or aromatic moiety of 2 to 16 carbons; R.sup.2 is —H, —F, or an alkyl of 1 to 6 carbon atoms; R.sup.3 is —F, —R.sup.4H.sub.(n-a)F.sub.a, —R.sup.5—O—R.sup.4H.sub.(n-a)F.sub.a, or —O—R.sup.4H.sub.(n-a)F.sub.a, wherein R.sup.4 is an alkyl or ether moiety of 1 to 30 carbons, R.sup.5 is an alkyl moiety of 1 to 30 carbons, a is an integer of 3 to n, and n is twice the number of carbon atoms in the alkyl moiety plus 1; m is between about 4 and 500, p is between about 4 and 150, q is between about 1 and 150; and r is an integer; with an acyl reagent of the formula O.sub.2N—R.sup.1C(O)X, wherein R.sup.1 is an aliphatic or aromatic hydrocarbon moiety of 1 to 10 carbon atoms and X is selected from the the group consisting of bromide, chloride and iodide, —H, —OH, and —OR.sup.8, wherein R.sup.8 is an alkyl of 1 to 3 carbon atoms to provide a nitro-terminated oligomer; b. hydrogenating the nitro-terminated oligomer under hydrogenation conditions including the presence of a hydrogenation catalyst to convert nitro moieties to amine moieties and provide a diamine-terminated oligomer; and c. reacting the diamine-terminated oligomer with at least one of (i) a dianhydride of the formula
O(C(O)).sub.2—L—(C(O)).sub.2O   (I) wherein L is a hydrocarbyl-containing moiety of 2 to 100 carbon atoms, optionally containing divalent radicals selected from the group consisting of oxygen, silyl, sulfur, carbonyl, sulfonyl, phosphonyl, perfluoro, tertiary amino, and imido; in the presence of one or more diamines of the formula
—NH—Z—NH—  (II) wherein: Z is a hydrocarbyl-containing moiety of 1 to 100 carbon atoms, optionally containing divalent radicals selected from the group consisting of oxygen, sulfur, silyl, carbonyl, sulfonyl, phosphonyl, perfluoro, tertiary amino, and imido, and (ii) an anhydride-terminated prepolymer of (I) and (II) having an weight average molecular weight of between about 1000 and 500,000, under condensation polymerization conditions to provide the copoly(amide acid oxetane).

4. A process for making a copoly(imide oxetane) comprising subjecting the copoly(amic acid oxetane) of claim 1 to imidization conditions.

5. The process of claim 4 wherein the imidization conditions comprise a thermal ring closure at a temperature of between about 150° C. and 400° C.

6. The process of claim 4 wherein the imidization conditions comprise a chemical ring closure in the presence of a ring-closing catalyst at a temperature between about −20° C. and 200° C.

7. The process of claim 6 wherein the ring-closing catalyst is pyridine, triethylamine, or acetic anhydride.

8. A copoly(imide oxetane) made by the process of claim 4.

Description

DETAILED DISCUSSION

Definitions and Procedures

(1) Water contact angle as used herein is the angle that deionized water contacts the surface of the polymer. A FTA 1000B contact angle goniometer available from First Ten Angstroms, Inc., Portsmouth, Va., United States can be used to measure the water contact angle using an 8 milliliter drop.

(2) Polyimides

(3) Polyimides are typically prepared by the reaction between a diamine and a dianhydride under condensation polymerization conditions although it is possible to prepare polyimides by other reactions such as that of a dianhydride and a diisocyanate or a diester of the dianhydride with a diamine. The copoly(imide oxetane)s of this invention use as all or a portion of the diamine component a diamine which is a derivative of a fluorine-containing oxetane oligomer, herein called a FOX diamine.

(4) The FOX diamine preferably constitutes a minor portion by mass of the diamine components used in the synthesis, often less than about 20, preferably less than about 10, and most times between about 0.02 to 0.5, mass percent of the total diamine where the properties of the polyimide are sought. Generally, the amount of FOX diamine is sufficient to provide a water contact angle of at least 85°, preferably at least 90°.

(5) The FOX diamine can be represented by the structure:
—N—R.sup.1—C(O)—O-J-C(O)—R.sup.1—N—
as discussed above. One or more FOX diamines can be contained in the copoly(imide oxetane)s of this invention.

(6) The optional diamine may be one or more aliphatic or aromatic diamines and includes diamines containing other hetero atoms. One or more other diamines may be used. Examples of diamines include aliphatic diamines such as trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, octamethylenediamine and nonamethylenediamine; and an alicyclic diamine such as bis(4-aminocyclohexyl)methane and bis(4-amino-3-methylcyclohexyl)methane; aromatic diamines, for example, phenylenediamine, diaminotoluene, 2,4-diaminomesitylene, 3,5-diethyl-2,6-diaminotoluene, xylylenediamine (in particular, metaxylylenediamine, paraxylylenediamine), bis(2-aminoethyl)benzene, biphenylenediamine, a diamine having a biphenyl backbone (e.g., 4,4′-diamino-3,3′-ethylbiphenyl), adiamine having adiphenyl alkane backbone [e.g., diaminodiphenylmethane, bis(4-amino-3-ethylphenyl)methane, bis(4-amino-3-methylphenyl)methane, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2,2′-bis(4-aminophenyl)propane], bis(4-aminophenyl)ketone, bis(4-aminophenyl)sulfone, or 1,4-naphthalenediamine, and an N-substituted aromatic diamine thereof; alicyclic diamine such as 1,3-cyclopentanediamine, 1,4-cyclohexanediamine, and bis(4-amino-3-methylcyclohexyl)methane; an aliphatic amine, such as trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, and octamethylenediamine, and an N-substituted aliphatic diamine thereof; and ether diamines such as poly(alkylene ether)diamines including poly(ethylene ether)diamine, poly(propylene ether)diamine, poly(tetramethylene ether)diamine; random or block copolymers of ethylene oxide and propylene oxide including propylene oxide and poly(propylene oxide) terminated poly(ethylene ether)diamine, 4,4′-oxydianiline; and aminated random or block copolymers of tetrahydrofuran with minor amounts of a second monomer such as ethylene oxide, propylene oxide, methyl tetrahydrofuran, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-bis[4-(4-aminophenoxy)phenyl]ethane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4′-bis(3-aminophenoxy)biphenyl, 4,4′-bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl] ketone, bis[4-(4-aminophenoxy)phenyl] ketone, bis[4-(3-aminophenoxy)phenyl] sulfide, bis[4-(4-aminophenoxy)phenyl] sulfide, bis[4-(3-aminophenoxy)phenyl] sulfone and bis[4-(4-aminophenoxy)phenyl] sulfone.

(7) Any suitable dianhydride or dianhydride combination can be used to make the copoly(imide oxetane) and one or more dianhydrides can be used. Aliphatic and aromatic dianhydrides can find application in making the copoly(imide oxetane)s of this invention. Examples of useful dianhydrides of the present invention include pyromellitic dianhydride (PMDA); 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA); 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA); 4,4′-oxydiphthalic anhydride (ODPA); 3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA); 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA); 2,3,6,7-naphthalene tetracarboxylic dianhydride; 1,2,5,6-naphthalene tetracarboxylic dianhydride; 1,4,5,8-naphthalene tetracarboxylic dianhydride; 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride; 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride; 2,3,3′,4′-biphenyl tetracarboxylic dianhydride; 2,2′,3,3′-biphenyl tetracarboxylic dianhydride; 2,3,3′,4′-benzophenone tetracarboxylic dianhydride; 2,2′,3,3′-benzophenone tetracarboxylic dianhydride; 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride; 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride; 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride; bis(2,3-dicarboxyphenyl)methane dianhydride; bis(3,4-dicarboxyphenyl)methane dianhydride; 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA); bis(3,4-dicarboxyphenyl)sulfoxide dianhydride; tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride; pyrazine-2,3,5,6-tetracarboxylic dianhydride; thiophene-2,3,4,5-tetracarboxylic dianhydride; phenanthrene-1,8,9,10-tetracarboxylic dianhydride; perylene-3,4,9,10-tetracarboxylic dianhydride; bis-1,3-isobenzofurandione; bis(3,4-dicarboxyphenyl)thioether dianhydride; bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylicdianhydride; 2-(3′,4′-dicarboxyphenyl).sub.5,6-dicarboxybenzimidazole dianhydride; 2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzoxazole dianhydride; 2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzothiazole dianhydride; bis(3,4-dicarboxyphenyl)2,5-oxadiazole 1,3,4-dianhydride; 2,5-(3′,4′-dicarboxydiphenylether) 1,3,4-oxadiazole dianhydride; butane-1,2,3,4-tetracarboxylic dianhydride; pentane-1,2,4,5-tetracarboxylic dianhydride; cyclobutane tetracarboxylic dianhydride; cyclopentane-1,2,3,4-tetracarboxylic dianhydride; cyclohexane-1,2,4,5 tetracarboxylic dianhydride; cyclohexane-2,3,5,6-tetracarboxylic dianhydride; 3-ethyl cyclohexane-3-(1,2)5,6-tetracarboxylic dianhydride; 1-methyl-3-ethyl cyclohexane-3-(1,2)5,6-tetracarboxylic dianhydride; 1-ethyl cyclohexane-1-(1,2),3,4-tetracarboxylic dianhydride; 1-propylcyclohexane-1-(2,3),3,4-tetracarboxylic dianhydride; 1,3-dipropylcyclohexane-1-(2,3),3-(2,3)-tetracarboxylic dianhydride; dicyclohexyl-3,4,3′,4′-tetracarboxylic dianhydride; 4,4′-bisphenol A dianhydride; 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride; bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylicdianhydride; hydroquinonediphthalic anhydride; ethyleneglycol bis(trimellitic anhydride); 9,9-bis-(trifluoromethyl)xanthenetetracarboxylic dianhydride (6FCDA); 9-phenyl-9-(trifluoromethyl)xanthenetetracarboxylic dianhydride (3FCDA); 9,9-diphenyl-2,3,6,7-xanthenetetracarboxylic dianhydride (PPXDA); 9,9-diphenyl-2,3,6,7-tetramethylxanthene (TMPPX); 9,9-diphenyl-2,3,6,7-xanthenetetracarboxylic bis(p-anisidylimide); 9,9-diphenyl-2,3,6,7-xanthenetetracarboxylic bis(butylimide); 9,9-diphenyl-2,3,6,7-xanthenetetracarboxylic bis(p-tolylimide); 9-phenyl-9-methyl-2,3,6,7-xanthenetetracarboxylic dianhydride (MPXDA); 9-phenyl-9-methyl-2,3,6,7-xanthenetetracarboxylic bis(propylimide); 9-phenyl-9-methyl-2,3,6,7-xanthenetetracarboxylic bis(p-tolylimide); 9,9-dimethyl-2,3,6,7-xanthenetetracarboxylic dianhydride (MMXDA); 9,9-dimethyl-2,3,6,7-xanthenetetracarboxylic bis(propylimide); 9,9-dimethyl-2,3,6,7-xanthenetetracarboxylic bis(tolylimide); 9-ethyl-9-methyl-2,3,6,7-xanthenetetracarboxlylic dianhydride (EMXDA);); 9,9-diethyl-2,3,6,7-xanthenetetracarboxylic dianhydride (EEXDA); etc. Many of the above mentioned dianhydrides (if not all) can also be used in their ‘tetra-acid form’ (or as mono, di, tri, or tetra esters of the tetra acid), or as their diester acid halides (chlorides). In some embodiments of the present invention however, the dianhydride form is generally preferred because it is generally more reactive than the acid or the ester.

(8) Typically the reaction is conducted in the presence of one or more organic solvents for the dianydride and diamine. Exemplary solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyridine, picoline, dimethylsulfoxide, dimethylsulfone, tetramethylurea and hexamethylphosphoramide. The reaction temperature is normally between about 15° C. and 75° C., preferably less than about 50° C. The reaction can be carried out under any pressure and ambient pressure is satisfactory. The reaction is typically conducted under any dry inert atmosphere such as nitrogen, helium, and argon. The reaction time depends upon the reactive nature of the reactants, solvent and reaction temperature. The reaction is usually continued for sufficient time to complete formation of a copoly(amic acid oxetane) which is usually from about 0.1 to 50 hours, say, about 2 to 30 hours. The copoly(amic acid oxetane) can be thermally imidized, resulting in the evolution of water, by heating, e.g. at a temperature of at least about 120° C., and often from about 150° C. to 400° C., or chemically imidized.

(9) FOX Diamines

(10) The FOX diamines used in making the copoly(imide oxetane)s of this invention can be represented by the structure
NH.sub.2—R.sup.1—C(O)—O-J-C(O)—R.sup.1—NH.sub.2
where J, R.sup.1, R.sup.2, R.sup.3 and m are as defined above.

(11) One source of FOX diamines uses fluorine-containing oxetane oligomers where the oligomers are functionalized to provide the diamine. The functionalization may proceed by any suitable process. A particularly advantageous process is to react hydroxyl-terminated oligomer with an acyl reagent containing a nitro substituent under nucleophilic reaction conditions to provide a di-nitro functionalized oligomer. The di-nitro functionalized oligomer can be readily hydrogenated under hydrogenation conditions, especially mild hydrogenation conditions, to provide the FOX diamine.

(12) The hydroxyl-terminated fluorine containing oxetane oligomers can be represented by the structure:
H—O-J-H
where J is as defined above. Examples of the oligomers include, but are not limited to, oligomers made from one or more of 3-(2,2,2-trifluoroethoxymethyl)-3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-oxetane, 3-(2,2,2-trifluoroethoxymethyl)-3-(3,3,4,4,5,5,6,6,7,7,8,8,8-trifluorooctyloxymethyl)oxetane, 3-(2,2,3,3,4,4,4-heptafluoro-butoxymethyl)-3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyloxymethyl)oxetane, 3-(2,2,2-trifluoroethoxymethyl)-3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-decyloxymethyl)oxetane and 3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-(3,3,4,4,5,5,-6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorodedecyloxymethyl)oxetane, and block oligomers with diols and hydroxyl-terminated oligomers such as ethylene glycol, propylene glycol, 1,3-propanediol, butanediol, poly(alkylene ethers) including poly(ethylene ether), poly(propylene ether), poly(tetramethylene ether); random or block copolymers of ethylene oxide and propylene oxide including propylene oxide and poly(propylene oxide), random or block copolymers of tetrahydrofuran with minor amounts of a second monomer such as ethylene oxide, propylene oxide, methyl tetrahydrofuran, bis[4-(3-hydroxyphenoxy)phenyl]methane, bis[4-(4-hydroxyphenoxy)phenyl]methane, 1,1-bis[4-(3-hydroxyphenoxy)phenyl]ethane, 1,1-bis[4-(4-hydroxyphenoxy)phenyl]ethane, 1,2-bis[4-(3-hydroxyphenoxy)phenyl]ethane, 1,2-bis[4-(4-hydroxyphenoxy)phenyl]ethane, 2,2-bis[4-(3-hydroxyphenoxy)phenyl]propane, 2,2-bis[4-(4-hydroxyphenoxy)phenyl]propane, 2,2-bis[4-(3-hydroxyphenoxy)phenyl]butane, 2,2-bis[4-(4-hydroxyphenoxy)phenyl]butane, 2,2-bis[4-(3-hydroxyphenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-hydroxyphenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4′-bis(3-hydroyphenoxy)biphenyl, 4,4′-bis(4-hysroxyphenoxy)biphenyl, bis[4-(3-hydroxyphenoxy)phenyl] ketone, bis[4-(4-hydrosyphenoxy)phenyl] ketone, bis[4-(3-hysroxyphenoxy)phenyl] sulfide, bis[4-(4-hydroxyphenoxy)phenyl] sulfide, bis[4-(3-hydroxyphenoxy)phenyl] sulfone and bis[4-(4-hydroxyphenoxy)phenyl] sulfone.

(13) The nucleophilic reaction conditions to convert a hydroxyl-terminated oxetane oligomer to a di-nitro functionalized oligomer can vary widely and optimal conditions will depend upon the acyl reagent used. The acyl reagent is generally present in a stoichiometric excess of that required for the nucleophilic reaction with both hydroxyls of the oligomer, say, a mole ratio of acyl reagent to hydroxyl on the oligomer of between about 1.1:1 to 10:1, and most often between about 1.5:1 to 5:1. Typically the reactions are conducted in the presence of one or more organic solvents for the oligomer and a base. The solvent and the base may be the same or different. Advantageously the base is an organic amine. The base is preferably present in an amount in excess of that required to neutralize the co-product of the nucleophilic reaction. Often the mole ratio of base to acyl reagent is at least about 2:1, and more frequently in the range of about 5:1 to 50:1. The reaction temperature is normally between about 10° C. and 120° C., preferably about 30° C. to 80° C. Preferably the reaction menstruum is under stirring and the acyl reagent is gradually added to avoid undue exotherms. The reaction can be carried out under any pressure and ambient pressure is satisfactory. The reaction is typically conducted under any dry inert atmosphere such as nitrogen, helium, and argon. The reaction time depends upon the reactive nature of the reactants, solvent and reaction temperature. Usually the reaction is complete in about 0.01 to 20 hours.

(14) Exemplary bases that can serve as solvents include trimethylamine, triethylamine, tripropylamine, tributylamine, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide. Other solvents include ethanol, n-propanol, isobutanol, butanol, hexanol, cyclohexanol, cyclohexane, hexane, benzene, toluene, xylene, methylene chloride, ethylene dichloride, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 3-methylphenol, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyridine, picoline, dimethylsulfoxide, dimethylsulfone, tetramethylurea and hexamethylphosphoramide.

(15) The acyl reagent is preferably an acyl halide such as a bromide, chloride or iodide with chlorides being most preferred. Examples of nitro-substituted acyl reagents include, without limitation, 3-nitrobenzaldehyde, 3, nitrobenzoic acid, methyl 3-nitrobnzoate, 3-nitrobenzoyl chloride, 4-nitrobenzoyl chloride, 3-nitrobenzoyl bromide, 4-nitrobenzoyl bromide, 3-nitrobenzoyl iodide, 4-nitrobenzoyl iodide, nitroacetyl bromide, nitroacetyl chloride, nitroacetyl iodide, nitropropionyl chloride, nitrobutyryl chloride, nitrovaleryl chloride, nitrocaproyl chloride, and isomers and lower alkyl and halo-substituted compounds thereof.

(16) The dinitro-functionalized oligomer is then subjected to hydrogenation to convert the nitro groups to amino groups. As the nitro groups are readily hydrogenated to amino groups, mild hydrogenations conditions can be used to prevent undue hydrogenation of other moieties in the oligomer. The hydrogenation is typically conducted in a solvent which may be the same or different from the solvent used in the nitro functionalization of the oligomers. Often, alkanol solvents are preferred. The hydrogenation is conducted in the presence of a catalytically effective amount of hydrogenation catalyst. Hydrogenation catalysts include platinum catalysts, such as, for example, platinum/carbon catalysts (Pt/C) or PtO.sub.2; palladium catalysts, such as, for example, Pd/C; rhodium catalysts, such as, for example, Rh/C, Rh/Al.sub.2O.sub.3 or Rh.sub.2O.sub.3; nickel catalysts, nickel/molybdenum catalysts such as, for example, Raney nickel; or iridium catalysts, and mixtures thereof. Special preference is given to Pd/C or Rh/C. Frequently the reaction menstruum is maintained under mixing such as stirring or agitation when conducted in a batch process. The hydrogenation temperature is usually in the range of about 10° C. to 120° C., preferably about 20° C. to 80° C. Hydrogen is provided at a pressure of between about 100 and 5000 kPa gauge, preferably between about 150 and 1000 kPa gauge. The duration of the reaction in batch mode is generally in the range of about 0.5 to 40 hours. In continuous processes, the reaction menstruum passes through a fixed catalyst bed, often at a liquid hourly space velocity of between about 0.5 and 10 hr.sup.−1.

EXAMPLES

(17) The following examples are to further illustrate the invention and are not in limitation thereof. All parts and percentages are by mass unless otherwise stated or clear from their context.

Example 1: Synthesis of Dinitro-Terminated Oxetane Oligomer

(18) This example uses a hydroxyl-terminated oxetane available as POLYFOX™ PF-6320, 3-(2,2,2-trifluoroethoxymethyl)-3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-oxetane oligomer having an approximate molecular weight of 3400 g/mole. To a glass flask blanketed with nitrogen which contains about 150 milliliters of toluene are charged 60.32 grams of the oligomer. Triethyl amine (14.52 grams) is added and the solution is stirred for about 10 minutes and heated to about 50° C. A previously prepared solution of 10.4 grams of p-nitrobenzoyl chloride dissolved in 150 milliliters of toluene is added to the oligomer-containing solution drop wise over a period of about 30 minutes. The solution is then stirred under reflux for about 16 hours, then cooled to room temperature. The solution is then filtered, washed twice (250 milliliters) with an aqueous solution of 5 mass percent sodium bicarbonate and then once with 250 milliliters of deionized, distilled water. Thereafter the solution is dried over magnesium sulfate. The liquor is then rotary evaporated to yield a viscous, honey-colored oil. The oil is vacuumed dried. The dried sample contains the dinitro-terminated oxetane oligomer.

Example 2: Synthesis of Diamine-Terminated Oxetane Oligomer

(19) A 100 milliliter, mechanically stirred, glass reaction vessel is charged with 8.8 grams of the dinitro-terminated oxetane oligomer of Example 1, 0.445 grams of palladium on carbon hydrogenation catalyst available from Aldrich Chemical Co. having a metal loading of 5 mass percent, and 40 milliliters of anhydrous ethanol. The resulting solution is degassed and subsequently backfilled with hydrogen to 200 kPa gauge. The solution is maintained under agitation for 16 hours. After removing hydrogen, the solution is filtered through diatomaceous earth (CELITE™ available from Celite Corporation, Goleta, Calif., United States) followed by rotary evaporation and vacuum drying. The dried sample contains the diamine of the oxetane oligomer.

Example 3: Synthesis of Copoly(Imide Oxetane)

(20) A series of copoly(imide oxetane)s are prepared using the following general procedure: 1. The diamine-terminated oxetane oligomer is dissolved in N,N-dimethylacetamide to provide an oligomer solution. 2. The other diamine, 4,4′-oxydianiline, is added to a stirred, glass reaction flask and dissolved in N,N-dimethylacetamide. 3. An amount of the oligomer solution is added to the flask to provide a sought mass ratio of the oxetane oligomer to the diamine. 4. The solution in the flask is stirred for about 10 minutes and then dianhydride, 3,3′,4,4′-bisphenyltetracarboxylic dianhydride, is added to the flask. The amount of dianhydride added provides a molar ratio of dianydride to total diamine of about 1.0:0.95. Sufficient N,N-dimethylacetamide is added to provide a 20 mass percent solids solution. 5. The solution is stirred at ambient temperature (about 22° C.) for about 16 hours under an inert gas atmosphere.

(21) The solution contains copoly(amic acid oxetane). Table I summarizes the polymers made.

Example 4: Imidization to Copoly(Imide Oxetane)

(22) Imidization of the polymer material is done using the following general procedure. Samples of each solution made in Example 3 are centrifuged to remove gas bubbles. A film is cast from each sample using a doctor blade to an approximate thickness of about 500 to 750 microns on glass and each film is placed in a forced air drying chamber at room temperature for about 24 to 48 hours to remove solvent and provide a tack-free surface. Some of the films are then thermally imidized under nitrogen using a cure cycle with stages at 150° C., 175° C., 200° C. and 250° C. with a minimum hold of 40 minutes at each stage.

(23) Some of the copoly(amic acid oxetane) solutions are chemically imidized by reaction with acetic anhydride and pyridine. In this procedure, 33.02 grams of a 10 mass percent solids copoly(amic acid oxetane) and N,N-dimethylacetamide solution are poured into a 100 milliliter 3-necked round bottomed flask. Then 3.9 milliliters of pyridine and 3.3 milliliters of acetic anhydride are added to the flask and the reaction mixture is mechanically stirred overnight under an inert atmosphere. After about 16 hours the reaction mixture is poured into a blender containing water resulting in precipitation of the chemically imidized copoly(imide oxetane) product. The copoly(imide oxetane) is filtered, stirred in hot water for several hours, filtered again and allowed to dry.

Example 5: Evaluation of Copoly(Imide Oxetane)

(24) The cast and imidized coatings are evaluated for various characteristics and performance properties.

(25) Modulus of the coatings is determined using a Sintech 2W test frame with a crosshead speed of 5.08 millimeters per minute and analyzed using Testworks 8.0 software (both available from MTS Systems Corporation, Eden Prairie, Minn., United States). See Table I.

(26) A ThermoFisher™ ESCA lab 250 X-ray photoelectron spectrometer (available from Thermofisher Scientific, Waltham, Mass., United States) is used for XPS analysis.

(27) A FTA 1000B contact angle goniometer available from First Ten Angstroms, Inc., Portsmouth, Va., United States is used to measure the water contact angle with an 8 microliter drop being used. See Table I.

(28) Dust adhesion is evaluated by adhering a 6 millimeter diameter sample of the cast film on the end of a sonication device. The surface is coated with an approximate monolayer of particles having a particle diameter of less than about 30 microns. The sonication device uses a series of sonication steps of increasing magnitude.

(29) With respect to dust adhesion, the copoly(imide oxetane)-containing films exhibit improved surface clearance and potentially lower adhesion values than the homopolymer.

(30) The XPS surface analysis indicates that the fluorine population of the exterior (air-facing) surface of the coating films reaches a plateau at a low fluorine-containing oxetane moiety content in the copoly(imide oxetane) material. The data are presented in Table I. For sake of comparison, the fluorine atomic concentration of the oxetane oligomer is about 29 atomic percent. The interior surface (glass-facing surface) has a fluorine population higher than that of the bulk, but less than that of the exterior surface (air-facing surface) which is also reported in Table I. The XPS analysis thus confirms an unexpected migration of the fluorine-containing oxetane moieties in the copoly(imide oxetane) to the surface, and further indicates that only a very small amount of the oxetane oligomer is required to provide sought low surface energies. Although the presence of the oxetane oligomer does not unduly adversely affect the mechanical properties of the copoly(imide oxetane) at somewhat higher levels, the ability to achieve the low surface energies with very small amounts of the oxetane oligomer would not detract from the desirable bulk properties of the copoly(imide oxetane) material.

(31) TABLE-US-00001 TABLE I Elon- Exterior Glass Diamine gation Surface Surface oxetane Break at Water Fluorine, Fluorine, oligomer, Modulus, Stress, Break, Contact Atomic Atomic mass % MPa MPa % Angle, ° % % 0 3590 141 10.1 81 5 2 0.01 3560 142 8.3 93 0.1 3570 142 9.2 95 14 5 0.2 3510 139 11.5 95 14 0.4 3450 138 7.5 94 20 0.5 3350 142 5.5 94 16 9 0.8 3460 138 11.2 94 17 1.0 3440 141 8.7 98 19 8 2.0 3380 138 8.7 94 17 5.0 3140 126 9.7 95 18 4