Abstract: A method for the preparation of a polyimide containing reversible crosslinks comprising the step of curing a monomer having the formula ##STR1## wherein R and R' may be the same or different and each is H or lower alkyl having 1-5 carbon atoms under conditions conducive to the formation of a polyimide and thereby forming a polyimide having the formula ##STR2## R and R' are as defined above and n is an integer from 10 to 100. The polyimide may be converted to a soluble polymer by cleaving the disulfide bond in the presence of a solvent and a reducing agent. The reduced polymer may be reformed into the polymer in an oxidation step or into a modified polyimide in other reaction steps. Copolymerization processes are also disclosed.

Abstract: This invention relates to insulated wires having good heat resistance and solderability. In particular, wires coated with a polyimide resin or an imide-modified polyurethane resin are provided. They can each be produced by coating a conductor with an insulating coating composition which contains a polyamic acid represented by the following formula: ##STR1## wherein R.sup.1 means a particular tetravalent organic group, R.sup.2 denotes a specific divalent organic group, X is an alkylene or alkylenephenylene group, and n stands for a positive integer.

Abstract: A photoconductive imaging member comprised of a supporting substrate, a photogenerating layer comprised of a ladder polymer selected from the group consisting of those represented by the following formulas: ##STR1## and mixtures thereof, wherein n represents the number of segments, and a charge transport layer.

Abstract: The invention comprises curing polyamic acid solutions into polyimide solutions by adding a hydrophilic reagent to a polyamic acid solution. The hydrophilic reagent is selected to have little or no reactivity with amines or carboxylic acids, and is of the type that will react with water to form by-products that shift the equilibrium between polyamic acid as a reactant and polyimide and water as products toward the production of polyimide.

Abstract: Disclosed is a polyimide ammonium salt comprising the reaction product of an ethylenically unsaturated amine with an aromatic polyimide having pendant carboxylic acid groups, said polyimide comprising the reaction product of diamine and aromatic dianhydride, where the diamine comprises an aromatic carboxylic acid diamine having at least one carboxylic acid. A substrate can be coated with the polyimide ammonium salt by forming a composition of a crosslinking agent and a solution of the polyimide salt in an organic solvent, spreading the composition on the substrate, evaporating the solvent to form a coating, exposing at least some of the coating to actinic radiation to crosslink and insolubilize the exposed portions of the coating, and washing the unexposed portions away by dissolving them in an organic solvent.

Abstract: The terminal-modified imide oligomer composition capable of being cured within a short time and of being converted to a shaped, cured resin article having a high mechanical strength, heat resistance and elastic modulus, comprises a rigid, high molecular weight aromatic polyimide (I) produced by polymerizing and imidizing a tetracarboxylic acid component comprising at least one biphenyltetracarboxylic acid compound with an amine component comprising at least one aromatic diamine compound (a) having at least one cyclic structure and two amino groups directly attached to the cyclic structure; a flexible imide oligomer (II) produced by polymerizing and imidizing the tetracarboxylic acid component, with a diamine component comprising at least one aromatic diamine compound (b) having at least two cyclic structures and two amino groups attached directly or through a divalent bonding member to the cyclic structures and a monoamine component comprising at least one monoamine compound (c) having an unsaturated hydrocar

Abstract: A method and apparatus are disclosed for conducting a physical process and a chemical reaction by exposing a material containing a volatile substance to microwave radiation where the morphology of said material will change when exposed to such radiation. The power of said radiation is adjusted over time as the morphology of the material changes to maximize the effect of the radiation in order to produce a product in a minimum amount of time that is substantially free of said volatile substance.The method and apparatus can also be used to conduct such a process or reaction with materials that do not contain a volatile material.In one embodiment a method and apparatus are disclosed for manufacturing a polyimide from a precursor in a solvent by exposing the precursor to microwave radiation in a tuneable microwave resonant cavity that is tuned during imidization to achieve critical coupling of the system. Microwave power is controlled to remove the solvent and obtain the desired level of reaction.

Abstract: A perfluorinated polyimide comprising a repeating unit represented by general formula (1): ##STR1## and a perfluorinated poly(amic acid) comprising a repeating unit represented by general formula (6): ##STR2## wherein R.sub.1 is a tetravalent organic group; and R.sub.2 is a divalent organic group, provided that chemical bonds between carbon atoms and monovalent elements contained in R.sub.1 and R.sub.2 are exclusively carbon-to-fluorine bonds; methods for preparing them; and optical material including the perfluorinated polyimide. 1,4-Bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride, 1,4-difluoropyromellitic anhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene, 1,4-difluoropyromellitic acid, and 1,4-bis(3,4-dicyanotrifluorophenoxy)tetrafluorobenzene as well as methods preparing them. The perfluorinated polyimide has a thermal stability and has a low optical loss in an optical communication wavelength region (0.8 to 1.7 .mu.m).

Abstract: A novel aromatic diamine; a polyimide comprising 1,3-bis(3-aminobenzoyl)benzene or 4,4'-bis(3-aminobenzoyl)biphenyl as a diamine component and having recurring structural units represented by the formula (III): ##STR1## wherein R is a tetravalent radical selected from the group consisting of an aliphatic radical having from 2 to 27 carbon atoms, alicyclic radical, monoaromatic radical, condensed polyaromatic radical, and noncondensed aromatic radical connected each other with a direct bond or a bridge member, and X is a divalent radical of ##STR2## and a polyimide having a terminal aromatic group which is essentially unsubstituted or substituted with a radical having no reactivity with amines or dicarboxylic acid anhydrides or a composition comprising said polyimide.

Abstract: A polyamic acid having a three-dimensional network molecular structure produced by a gel forming ring-opening polyaddition reaction in an organic solvent of the reaction components comprising:(A) an acid component consisting of at least one tetracarboxylic acid dianhydride selected from the group consisting of a tetracarboxy benzene dianhydride, a tetracarboxy dianhydride of a compound having 2 to 5 condensed benzene rings, and compounds represented by formula (III), and substituted compounds thereof: ##STR1## wherein R.sub.1 represents --O--, --CO--, --SO.sub.2 --, --SO--, an alkylene group, an alkylene bicarbonyloxy group, an alkylene bioxycarbonyl group, a phenylene group, a phenylene alkylene group, or a phenylene dialkylene group, n.sub.4 is 0 or 1, n.sub.5 is 0 or 1; and n.sub.6 is 1 or 2, provided that the sum of n.sub.5 and n.sub.

Abstract: High performance, thermooxidatively stable polyimides are prepared by reacting aromatic diamines with pendant trifluoromethyl groups and dianhydrides in an amide solvent to form a poly(amic acid), followed by cyclizing the poly(amic acid) to form the corresponding polyimide, which has the following general structure: ##STR1##

Abstract: A high-temperature stable, highly optically transparent-to-colorless, low dielectric linear aromatic polyimide is prepared by reacting an aromatic diamine with 3,3'bis(3,4-dicarboxyphenoxy)diphenylmethane dianhydride in an amide solvent to form a linear aromatic polyamic acid. This polyamic acid is then cyclized to form the corresponding polyimide, which has the following general structural formula: ##STR1## wherein Ar is any aromatic or substituted aromatic group, and n is 10-100.

Abstract: A method for preparing polyimides comprising reacting carbon monoxide, a primary diamine and a reactant selected from the group consisting of bis(o-iodoaromatic ester)s and bis(o-bromoaromatic ester)s, in the presence of solvent and catalyst, said catalyst being a compound of a metal seIected from the group consisting of platinum, palladium and nickel.

Abstract: The present invention relates to new polyetherimideimides having imideimide group with the following structural formula(I) and inherent viscosity of 0.27.about.0.71 dl/g, which can be made by effecting reaction between an aromatic bis(ether anhydride) and an organic diamine or an aromatic bis(nitro imideimide) and a metal salt of diol.

Abstract: The semicrystalline polyimide prepared by reaction of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 1,3-bis(4-aminophenoxy-4'-benzoyl)benzene (1,3-BABB) is modified so that it can be more readily processed to form adhesive bonds, moldings and composites. The stoichiometric ratio of the two monomers, BTDA and 1,3-BABB is controlled so that the intermediate polyamide acid is of a calculated molecular weight. A polyamide acid with excess anhydride groups is then reacted with the stoichiometrically required amount of monofunctional aromatic or aliphatic amine required for complete endcapping. A polyamide acid with excess amino groups is reacted with the stoichiometrically required amount of monofunctional aromatic anhydride required for complete endcapping. The stoichiometrically offset, endcapped polyimide is processed at lower temperatures and pressures than the unmodified high molecular weight polyimide with the same repeat unit, and exhibits an improved melt stability.

Abstract: A catalyst component useful in propylene polymerization in combination with a dialkyl aluminum halide cocatalyst comprises the product of reaction of TiCl.sub.3 which is substantially free of extraneous halide with a selected electron donor compound which is dissolved in a liquid hydrocarbon solvent in which the TiCl.sub.3 is dispersed. The electron donor compound is selected from certain organic acid esters, hindered phenolic compounds and silyl esters.The catalyst of the invention provides increased activity, molecular weight control, increased isotacticity of propylene polymer products and prevents catalyst feed line pluggage, among other advantages.

Abstract: A hot-melt adhesive comprising a special polyamideimide or polyamide is excellent in heat resistance and adhesive strength and usable for providing substrates for printed circuit boards.

Abstract: In a process for the preparation of polyimide by reacting a diamine compound with tetracarboxylic dianhydride in a phenol based solvent, an improved process for reacting the diamine compound with tetracarboxylic dianhydride in a solution by forming separate solutions of the tetracarboxylic dianhydride and the diamine compound and mixing the solutions and/or by dissolving tetracarboxylic dianhydride in the phenol-based solvent containing an organic base.

Abstract: Polyimide which is obtained by polymerization and consists essentially of recurring structural units of the formula (I): ##STR1## wherein X is a single bond or a hexafluoroisopropylidene group, is processed to a form of pellet, followed by heat-treating to obtain crystallinity of 5% or more, and fed to an extruder to obtain articles.

Abstract: A tri-component polyimide copolymer and the process of preparing the copolymer are disclosed. A mixed reaction medium or solvent system comprising phenol and at least one compound of resorcinol, 1,6-dimethyl phenol and 4-methoxy phenol is used to produce the copolymer by direct imidization without isolating or purifying the imide oligomer as an intermediate.

Abstract: In one embodiment this invention provides polymalonamide polymers with side chains which exhibit nonlinear optical response.

Abstract: Azole rings, such as oxazole and thiazole rings, can activate an aromatic ring bonded to a leaving group such as a halogen atom so that the aromatic ring will undergo aromatic nucleophilic substitution. The reaction is useful for making ethers, thioethers and amines containing azole rings. In particular, monomers having azole rings, activated aromatic rings with leaving groups and nucleophilic moieties can react under conditions of aromatic nucleophilic displacement to form non-rigid rob PBZ polymers. The non-rigid rod PBZ polymers can be used to form molecular composites with rigid rod PBZ polymers which molecular composites are not substantially phase separated.

Abstract: A method for preparing high molecular weight polyethermide polymers in a dual solvent system is disclosed. The inventive method provides for polymerizing a diamine monomer and a dianhydride monomer in a solvent system comprised of at least two solvents, a first solvent is selected for its solubility characteristics such that the polyethermide polymer is highly soluble therein and a second solvent is selected for its relatively high boiling point characteristics such that when the second solvent and first solvent are mixed together, the boiling point of the dual solvent system is at least as high as the temperature at which polymerization of said monomers occurs. In one embodiment, a diamine monomer of 4,4'-sulfonyl dianiline (SDAN) is reacted with a dianhydride monomer of bisphenol A dianhydride (BPADA) in the presence of a catalyst and a chain stopper in a dual solvent system comprised of chloroform and ortho-dichlorobenzene. The resulting polyethermide has an intrinsic viscosity exceeding 0.

Abstract: Perfluoroalkylated diaminoesitylene and polymers, preferably polyimides, made therefrom. The necessarily obtainable meta-substitution position of the perfluoroalkyl group with respect to both amino-groups provides an improved diamine and compositions of matter resulting therefrom.

Abstract: Disclosed is an aromatic diamine having the general formula ##STR1## where A is a group containing at least one aromatic ring, each Y is independently selected from ##STR2## R is a group containing at least one olefinically unsaturated group, R' is hydrogen, alkyl to C.sub.25, aryl, or R, n is 1 to 4, and the number of olefinic groups in Y is at least 3 when each Y is ##STR3## and otherwise is at least 2. Photosensitive polyamic acids and polyimides can be prepared from the aromatic diamines which can be crosslinked with light to a mask to form patterns on a substrate.

Abstract: A new class of soluble phenylated polyimides made from 3,6-diarypyromellitic dianhydride and process for the manufacture of the 3,6-diarypyromellitic dianhydride starting material. The polyimides obtained with said dianhydride are readily soluble in appropriate organic solvents and are distinguished by excellent thermal, electrical and/or mechanical properties making the polyimides ideally suited as coating materials for microelectronic apparatii, as membranes for selective molecular separation or permeation or selective gas separation or permeation, or as reinforcing fibers in molecular composites, or as high modulus, high tensile strength fibers.

Abstract: Polyimide oligomers include (1) linear, monofunctional crosslinking oligomers prepared by condensing a monoanhydride end cap with a diamine that includes alternating ether and "Sulfone" (--SO.sub.2 --, --S--, --CO--, --(CF.sub.3).sub.2 C--, or --(CH.sub.3).sub.2 C--) linkages connecting alternating aromatic radicals and with a dianhydride (or dianhydride mixture), particularly the unsaturated, aliphatic dianhydride commonly known as MCTC; (2) linear, mono- or difunctional crosslinking oligomers prepared by condensing an amine end cap with a diamine and a dianhydride; and (3) multidimensional, crosslinking oligomers having an aromatic hub and at least three radiating arms connected to the hub, each arm including a crosslinking end cap at its distal end and at least one imide linkage.Blends, prepregs, and composites can be prepared from the oligomers.

Abstract: Polyimide resins, which have reduced anhydride content when molded, are prepared by a novel reaction process that includes reacting an esterified aromatic tetracarboxylic acid or anhydride monomer with a primary aromatic diamine until substantially no free monomer remains to form a polyamide-acid (the molar ratio of esterified monomer to diamine ranging from 1:1 to 1:2); reacting the polyamide-acid with a low molecular weight end-capping agent to form an end-capped polyamide-acid; and heating the end-capped polyamide-acid to form the polyimide.

Abstract: The present invention relates to a novel class of aromatic diamine monomers, benzoxazole polymers made from said class of monomers, and polymer-matrix composites which may be produced therefrom. The present invention also relates to methods of producing said polymers and said polymer-matrix composites. The polymer-matrix composites have as one advantage high strength and temperature resistance.

Abstract: An improved low toxicity polymerization of monomer reactants (PMR) system has 3,4'-oxydianiline as the key monomer reactant. One variation of this system, LaRC-RP46, is prepared by reacting together monomethyl ester or 5-norbornene-2,3-dicarboxylic acid (NE), 3,4'-oxydianiline (3,4'-ODA), and dimethyl ester of 3,3',4,4'-benzophenonetetracarboxylic acid (BTDE); this combination is then treated with heat. This new matrix resin is readily processed into a high quality graphite fiber reinforced composite with excellent reproducibility. The flexibility of the ether linkage in 3,4'-ODA provides high toughness. The composite retains excellent mechanical properties both at 316.degree. C. and at 371.degree. C. The development of LaRC-RP46 will significantly extend the applications of PMR type polyimides.

Abstract: Polyimide copolymers are disclosed having the recurring structure ##STR1## wherein AR is AR.sub.1 or AR.sub.2, wherein AR.sub.1 is ##STR2## and wherein AR.sub.2 is ##STR3## provided that the molar ratio of AR.sub.1 to AR.sub.2 is 3:1 to 1:3, and wherein AR.sub.3 is ##STR4## These polyimides have unexpected properties which are useful in various electronic applications.

Abstract: Formation of polyimide film with a preselected coefficient of thermal expansion is disclosed employing relationships between cure temperature and heating rates.

Abstract: Disclosed is an aromatic copolyimide film prepared by chemical conversion of a copolyamide acid solution obtained by copolymerization of an aromatic tetracarboxylic acid component comprising from 30 to 50 mole % of biphenyltetracarboxylic acid dianhydride, 50 to 70 mole % of pyromellitic acid dianhydride, 60 to 80 mole % of p-phenylenediamine and 20 to 40 mole % of 4,4'-diaminodiphenyl ether. The aromatic copolyimide film has a low coefficient of thermal expansion, low water absorption, a low coefficient of hygroscopic expansion, high mechanical strength and is readily etchable making it suitable for use an advanced electronic substrate.

Abstract: A polymeric acid is synthesized by the ring-opening poly-addition reaction using a biphenyl tetracarboxylic acid as a tetracarboxylic acid moiety and an aromatic diamine, particularly p-phenylene diamine, as a diamine moiety. An aromatic polyimide resin layer possessing a highly desirable heat-resisting property as a heat-resistant insulating coating material and excelling in adhesive strength relative to a substrate is obtained by adjusting the polymeric acid in viscosity with a suitable organic solvent, applying the resultant polyamic acid on a substrate, and firing the applied layer of the polyamic acid. The substrate, for example, is a conductor layer formed as with copper and used as a multi-layer wiring board for hybrid IC's.

Abstract: Partially fluorinated tetracarboxylic acid and the dianhydride thereof, a process for their preparation and their useA compound of the formula ##STR1## and the dianhydride thereof are prepared by air oxidation in the presence of a catalyst mixture composed of at least 2 heavy metal salts and also bromine in an acid organic medium. The compounds can be employed for the preparation of partially fluorinated polycondensates, such as polyimides, polycarboxamides, esters of polyamidecarboxylic acids, polyamides and imide-oligomers.

Abstract: The new aromatic ether imides corresponding to the following formula ##STR1## may be used for the production of plastics which in turn may be worked up into moulded articles, films, sheet products and filaments. The plastics produced from the new aromatic ether imides are distinguished by their exceptional dimensional stability under heat.

Abstract: A silicon-modified thermoplastic resin is prepared by heating a mixture comprised of 10 to 90% by weight of an imide group-containing thermoplastic resin and 90 to 10% by weight of a modified silicon compound having an amino group--NH.sub.2 at one end of the molecule and an alkyl group --C.sub.n H.sub.2n+1 (n is an integer of at least 1) at the other end of the molecule, to chemically bond the imide group-containing thermoplastic resin to the modified silicon compound.

Abstract: The invention is a novel polyimide prepared from 3,4'-oxydianiline (3,4'-ODA) and 4,4'-oxydiphthalic anhydride (ODPA), in 2-methoxyethyl ether (diglyme). The polymer has been prepared in ultra high molecular weight and in a controlled molecular weight form which has a 2.5 percent offset is stoichiometry (excess diamine) with a 5.0 percent level of phthalic anhydride as an endcap. This controlled molecular weight form allows for greatly improved processing of the polymer for moldings, adhesive bonding, and composite fabrication. The higher molecular weight version affords tougher films and coatings. The overall polymer structure groups in the dianhydride, the diamine, and a metal linkage in the diamine affords adequate flow properties for making this polymer useful as a molding powder, adhesive, and matrix resin.

Abstract: Fusible polyimide powders are prepared by the process of this invention. An amic acid amine is first prepared by treating (n+1) moles of a bis(aminophenyl)methane with n mole of aromatic tetracarboxylic anhdride to produce an aromatic amic acid prepolymer. This prepolymer is then mixed with an unsaturated carbocyclic monoanhydride and the mixture heated to form a reactive end-capped polyamic acid precursor. The resulting composition is thermally treated in order to partially imidize the precursor. The resulting fusible polyimide powder is finally separated.

Abstract: The present invention relates to a novel fluorine-containing diaminobenzene derivatives having a perfluoroalkyl group and to a novel fluorine-containing polyimide which is produced from the said diaminobenzene as a starting material and to a novel polyimide having both a fluorine-containing group and/or a siloxane chain in the side chain thereof, the polyimide being produced from the said fluorine-containing diaminobenzene and fluorine-containing polyimide and to a liquid crystal-aligning agent with an elevated tilt angle, which contains a polyimide having a fluorine-containing group and a siloxane chain.

Abstract: A method for the preparation of a variety of engineering polymers and copolymers, in particular aromatic polymers and copolymers which comprises reacting a stannylated reactant containing a first monomeric or polymeric moiety with an electrophilic reactant, usually a di(acid chloride) containing a second monomeric or polymeric moiety. The intermediate and second compound react by way of a condensation reaction to eliminate the tin and polymerise together the first and second moieties. Some novel polymers and copolymers can be prepared using this method.

Abstract: To produce flame-retardant thermostable new homopolyimides having structural units of the general formula ##STR1## by reacting 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride with an overall equimolar amount of 2,4- and/or 2,6-toluene diisocyanate, the reaction is carried out in the presence of a polymerization accelerator. The new homopolyimides have a glass transition point of at least 320.degree. C. and are processible to moulded articles exhibiting a similarly good structural strength as could hitherto be observed in mixed polyimides only. Furthermore, the new homopolyimides can be spun to fibres.

Abstract: Viscosity stable, essentially gel-free linear polyamic acids are provided by a process utilizing offset stoichiometry. Polyimides formed from such polyamic acids have low TCE and low dielectric constants.Methods for improved adhesion of polyimides are also disclosed.

Abstract: Copolyimides and their precursors are disclosed comprising units represented by the formula ##STR1## where R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same or different and are hydrogen or C.sub.1 to C.sub.6 linear or branched alkyl, with the proviso that R.sub.1, R.sub.2, R.sub.3 and R.sub.4 cannot simultaneously be hydrogen and where Z is a chemical bond, ##STR2## Ar is the tetravalent residue of a tetracarboxylic acid or acid dianhydride or di- or tetraester thereof, where x and y are integers from about 100 to about 1,000, and the ratio of x to y is from about 1:99 to about 49:51, and z is 0-5.These copolymers have improved resistance to stress cracking. They may also be used in applications such as coatings, or adhesives.

Abstract: The present invention provides for a novel heat stable class of polyamide-imide polymers having excellent flow properties and hydrolytic stability which are prepared by forming the polycondensation product of one or more aromatic or aliphatic diamines, one or more additional comonomers selected from the group consisting of a tetrafunctional aromatic dianhydride, an aromatic or aliphatic dicarboxylic acid (or acid derivative thereof) and mixtures thereof, and a comonomer comprising a tri- or hexafluoro-substituted tricarboxylic acid anhydride (or acid derivative thereof) having the structure: ##STR1## wherein Z is CF.sub.3 or a phenyl radical.

Abstract: A solution composition of a polyimide resin type curable resin having imide and alkoxysilyl groups is prepared by reacting a polyimide with a silicon compound in an organic solvent. The solution can be cured through relatively mild heating into coatings having enhanced substrate adherence and solvent resistance and thus suitable as protective coatings on electronic parts.

Abstract: The solvent-resistance and thermal stability of polyamideimides of the general formulae: ##STR1## is improved by capping the amideimides with a crosslinking functionality (Y) containing a residue selected from the group of: ##STR2## wherein R.sub.1 =lower alkyl, lower alkoxy, aryl, aryloxy, substituted alkyl, substituted aryl (either including hydroxyl or halo-substituents), halogen, or mixtures thereof;j=0, 1, or 2;G=--CH.sub.2 --, --O--, --S--, --SO.sub.2 --, --SO--, --CO--, --CHR--, or --CR.sub.2 --;R=hydrogen, lower alkyl, or phenyl;T=methallyl or allyl;Me=methyl;R.sub.2 =a trivalent organic radical; andR.sub.3 =a divalent organic radical.The amideimide oligomers may be linear or multidimensional, and can be processed into blends, prepregs, or composites. Methods of making these amideimides and intermediates useful in the syntheses are also described.

Abstract: A process for the synthesis of derivatives of materials containing an imide group conjugated to an aromatic moiety to form an ester, a thioester, an amide, a ketone, and silylesters. Electrons are supplied to redox sites to form a reduced imide material. The reduced imide material is contacted with a nucleophile which opens the imide ring of the reduced imide and chemically combines with a carbonyl carbon atom of the open imide ring to form an imide derivative.

Abstract: A reactive oligoimide, which may serve as an adhesive for bonding at least one layer or film to another layer, preferably a flexible metallic layer to a flexible layer of a polyimide, in order to form a flexible multilayer metal-clad laminate.

Abstract: A high-temperature stable, optically transparent, low dielectric aromatic polyimide is prepared by chemically combining equimolar quantities of an aromatic dianhydride reactant and an aromatic diamine reactant, which are selected so that one reactant contains at least one Si(CH.sub.3).sub.2 group in its molecular structure, and the other reactant contains at least one --CH.sub.3 group in its molecular structure. The reactants are chemically combined in a solvent medium to form a solution of a high molecular weight polyamic acid, which is then converted to the corresponding polyimide.