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: The thermooxidative stability and thermomechanical properties of advanced composites which use high performance resin matrices such as polyimides and high strength carbon fibers may be improved by sizing the carbon fibers with uncapped or capped linear polyamideimides.The uncapped linear polyamideimides useful as carbon fiber sizings generally contain repeating units having the general formula: ##STR1## wherein R.sub.2 =a trivalent organic radical and generally benzenetriyl;R.sub.3 =a divalent organic radical; andn=an integer sufficiently large to provide a strong, tough coating.Useful capped, linear polyamideimide oligomers may be formed by including end caps with an unsaturated functionality (Y) containing a residue selected from the group consisting of: ##STR2## wherein R.sub.1 =lower alkyl, lower alkoxy, aryl, aryloxy, substituted alkyl, substituted aryl, halogen, or mixtures thereof;j=0, 1, or 2;i=1 or 2;G=--CH.sub.2 --, --O--, --S--, --SO.sub.2 --, --SO--, --CO--, --CHR--, or --CR.sub.

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: Fully cyclized polyimides based on aromatic tetracarboxylic acid dianhydrides with substitution in the positions ortho to the bridging moiety and aromatic diamines, exhibiting solubility in organic solvents, increased glass transition temperatures, low coefficients of thermal expansion and photoimagability; said polyimides being suitable for the production of films, protective coatings and photolithographic relief images.

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: A thermosetting resin composition, a solution composition of the resin and a thermosetting dry film formed out of the resin are disclosed. The thermosetting resin composition contains a specific resin component as the main component. The resin component consists of (A) 100 weight parts of an aromatic polyimide; and (B) 5 to 2,000 weight parts of (a) a terminal-modified imide oligomer or (b) an unsaturated imide compound. The aromatic polyimide (A) is formed from a tetracarboxylic acid ingredient which contains 2,3,3',4'-biphenyltetracarboxylic acid or its derivative in an amount of at least 60 mole % and an aromatic diamine ingredient. The polyimide has such a high molecular weight that the logarithmic viscosity (concentration: 0.5 g/100 ml of solvent; solvent: N-methyl-2-pyrrolidone; and temperature of measurement: 30.degree. C.) is not less than 0.2. The polyimide is soluble in an organic polar solvent.

Abstract: The invention is a process for making novel branched polybenzazole polymers and the polymers formed thereby. Novel compounds are also disclosed that are useful as branching agents in making the branched polybenzazole polymers. The branched polymers synthesized by the process can be formed into strong, light articles such as fibers and films.

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 and a comonomer comprising a tri- or hexafluoro-substituted tricarboxylic acid anhydride (or acid derivative thereof) having the structure: ##STR1## wherein R is CF.sub.3 or a phenyl radical. In addition to improved flow properties, the polyamide-imide polymers of this invention also exhibit improved solubility properties in most organic solvents, good resistance to attack by chlorinated solvents such as trichloroethylene as compared with polyimides, improved hydrophobic properties as well as good thermal properties, including resistance to thermooxidative degradation.

Abstract: The present invention provides for hybrid polybenzimidazole and polybenzimidazolone polymers which are characterized as containing both imidazole and imidazolone structural units in the polymer chain. These polymers are characterized as containing at least one recurring monomer unit containing the structure of the formula: ##STR1## wherein Ar is a tetravalent aromatic moiety derived from an aromatic tetraamine and Ar.sub.1 is a trivalent aromatic moiety derived from a trifunctional acid, an acid anhydride or amine-reactive derivatives thereof, said polymers further characterized by an inherent viscosity of at least about 0.01 dl/g measured as a 0.5% solution in N-methyl pyrrolidone at 25.degree. C.The polymers of this invention exhibit many of the advantageous properties of both polybenzimidazole and polybenzimidazolone polymers. They are characterized as being extremely resistant to chemical attack such as by solvents, acids and bases.

Abstract: A preferred class of polyimide oligomers include (1) linear, difunctional crosslinking oligomers prepared by condensing an imidophenylamine end cap with a lower alkylene diamine or a polyaryldiamine such as 3,3'-phenoxyphenylsulfone diamine and with a dianhydride, particularly 4,4'-phenoxyphenylsulfone dianhydride; and (2) multidimensional, crosslinking, polyimide oligomers having an aromatic hub and at least two radiating arms connected to the hub, each arm including a crosslinking imidophenylamine end cap at its distal end and at least two imide linkages.Blends, prepregs, and composites can be prepared from the oligomers.

Abstract: Disclosed herein are processes for the preparation of polyimide-isoindroquinazolinediones and precursor thereof. These polymers are useful as heat-resistant electric insulation materials, surface coating films for electronic instrument parts and especially suitable for manufacturing a photoresist. The above precursor is produced by reacting a an alkylenebistrimellitate dianhydride, a diaminoamide compound and the other amine. The precursor is readily dehydrated and ring-closed to produce polyimide-isoindroquinazolinedione, which is often conveniently conducted by producing a varnish of the precursor, applying it onto adequate substrates such as silicon wafers, glass plates, metal plates, etc. and then subjecting the coated film to dehydration. The resulting films have excellent physical properties such as good adherence, high tensile strength, low elasticity, etc.

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: A thermoplastic, liquid-crystalline, wholly aromatic polyimide ester comprising(a) at least one structural unit derived from an aromatic dicarboxylic acid,(b) at least one structural unit derived from a substituted hydroquinone having an aralykyl substituent group in its benzene nucleus, and at least one structural unit selected from (c) structural units derived from carboxy-N-(carboxyphenyl)phthalimides and (d) structural units derived from carboxy-N-(hydroxyphenyl)phthalimidesis able to be molded by injection molding, has excellent dimensional stability and dimensional accuracy in both flow direction and a direction making a right angle with the flow direction, and is also excels in strength, elastic modulus, and heat resistance.

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: Polyetherimide resins which crystallize from the melt contain crystallizing repeating units based on biphenoldianhydride or hydroquinone dianhydride and a linear aromatic diamine. The melt crystalline polyetherimides exhibit improved solvent resistance. The melt crystalline polymers retain the advantageous properties associated with their known amorphous polyetherimide counterparts.

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: Novel polyimide based films are disclosed that are resistant to arc tracking and that include aromatic dianhydrides together with aromatic diamines and aliphatic diamines. The compositions contain from 5 to 20 percent by weight of the aliphatic diamine. These compositions maximize the thermal aging capability of the polyimide. The compositions are useful as films and laminates for wire and cable.

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 rod 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: Disclosed are rigid fluorinated monomers, their preparation, and polymers derived therefrom based on two novel tricyclic xanthene core systems, 9,9-bis(perfluoroalkyl)xanthene (I) and 9-phenyl-9-perfluoroalkylxanthene (II). The monomers have utility in the preparation of advanced high-performance polymers, particularly polyimides.

Abstract: The present invention provides cross-linkable polyimide polymers having at least one repeating unit of the sturcture of: ##STR1## wherein n is the number of repeating groups and A is a tetravalent aromatic organic radical wherein each pair of carbonyl groups are attached to adjacent carbons in the ring moiety A.It has been found that polyimides having the structure of formula I may be crosslinked at surprisingly low temperatures when heated from about 75 to about 110.degree. C. to form infusible and solvent resistant shapes, thereby rendering them useful in the preparation of films, laminates and composites where inertness to solvents is a prerequisite.

Abstract: Novel halogenated polyimides and co-polyimides comprise recurring imide structural units of the formula ##STR1## where X is F, Cl, Br or I; Y is H, F, Cl, Br or I; and R is a divalent organic radical.

Abstract: A process is disclosed for preparation of anhydrides containing additional carboxylic acid moieties and dianhydrides of disubstituted maleic anhydride compounds wherein the acid anhydrides and dianhydrides retain their alkene character. The resulting alkene compounds are useful as precursors for polyesters, thermally stable polyamide-imides and polyimides which are also disclosed, as well as a process for their preparation.

Abstract: The present invention relates to a paper releasing guide-claw for a copying machine and a method for producing the same including molding a material containing from about 50-90% by weight of a polyimide consisting essentially of recurring units of the formula: ##STR1## from about 5 to about 40% by weight of a fibrous reinforcing material, and from about 5 to about 30% by weight of a solid lubricant, wherein the sum of the content of the fibrous reinforcing material and the solid lubricant is from about 10 to about 50% by weight, heat treating the molded guide-claw at a temperature of from about 250.degree. C. to about 340.degree. C. for a time sufficient to increase the density of the polyimide component by 1.5%.

Abstract: Disclosed are rigid fluorinated monomers, their preparation, and polymers derived therefrom based on two novel tricyclic xanthene core systems, 9,9-bis-(perfluoroalkyl)xanthene (I) and 9-phenyl-9-perfluoroalkylxanthene (II). The monomers have utility in the preparation of advanced high-performance polymers, particularly polyimides.

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.

Abstract: Polyimides useful in multilayer electronic devices containing the 4,4'-bis(4-amino-2-trifluoromethylphenoxy) biphenyl moiety have low dielectric constants, low moisture uptake, high thermal degradation stability, low glass transition temperature.

Abstract: The present invention provides diamino compounds and liquid crystal aligning films comprising polyimides which are obtained from the said diamino compounds represented by the general formula: ##STR1## wherein R.sub.1 indicates an alkyl group having 3 to 22 carbon atoms, R.sub.2 indicates a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and R.sub.3 -R.sub.10 indicate a hydrogen atom or a methyl group, respectively.The liquid crystal aligning films are useful for STN mode display cells in realizing a high pretilt angle.

Abstract: The present invention provides a copolyimide characterized in that the copolyimide contains units represented by formulas (I) and (II) ##STR1## (wherein R.sub.0 represents an aromatic tetracarboxylic residue). The polyimide has excellent thermal dimensional stability, and can be fabricated by using conventional inexpensive materials.

Abstract: A co-polyimide based upon a mixture of 4,4'-oxydiphthalic dianhydride (ODPA) and 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA) as the dianhydride component and either 4,4'-oxydianiline (ODA) or paraphenylene diamine as the amine component is disclosed. The molar ratio between the ODPA and BPDA ranges from 3:1 to 1:3. The co-polyimide may either be formed as a random copolymer, or as a block copolymer where the blocks are based upon blocks of polymer containing ODPA and blocks of polymer containing BPDA provided that the molar ratios of ODPA and BPDA are in the ratio of 3:1 to 1:3.

Abstract: A new class of polyimides and copolyimides made from substituted benzidines and aromatic dianhydrides and other aromatic diamines. The polyimides obtained with said diamines are distinguished by excellent thermal, excellent solubility, excellent electrical properties such as very low dielectric constants, excellent clarity and mechanical properties making the polyimides ideally suited as coating materials for microelectronic apparatii, as membranes for selective molecular or gas separation, as fibers in molecular composites, as high tensile strength, high compression strength fibers, as film castable coatings, or as fabric components.

Abstract: The present invention provides polyamide-polyimide and polybenzoxazole-polyimide polymers derived therefrom with improved processing and film characteristics having incorporated into the polymeric backbone the polymeric condensation residuum of novel aromatic diamino compounds having the formula: ##STR1## wherein A is selected from the group consisting of SO.sub.2, O, S, CO, C.sub.1 to C.sub.6 alkyl, perfluoroalkyl or perfluoroarylalkyl having from 1 to 10 carbon atoms and a carbon-carbon double bond directly linking the two aromatic groups, and R is hydrogen.The polyamide-polyimide polymers of this invention are prepared by reacting compounds of the above formula, alone or admixed with other aromatic diamines, with one or more aromatic tetracarboxylic acids or anhydrides thereof. Polybenzoxazole-polyimide derivatives of such polyamide-polyimide.

Abstract: Disclosed is a film of polyimide having repeating units of formula (1) and a birefringence (.DELTA.n) of at least 0.13: ##STR1## wherein R.sup.1 is an aromatic group having a valency of 4, at carbon atoms constituting the aromatic ring, and R.sup.2 is an aromatic group having a valency of 2, at carbon atoms constituting the aromatic ring. This polyimide film exhibits good thermal dimensional stability.

Abstract: In humid atmospheres (e.g., 40% relative humidity or above) solutions of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride/2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane polyimides tend to be unstable in the sense that during spin coating operations undesirable precipitate formation occurs on the rotating surface of the wafer. The result is the formation of unacceptable coatings due to their irregularity and lack of uniformity. Described are solutions of these polyimide polymers in a solvent containing one or more liquid aromatic hydrocarbons having a boiling point at least about 110.degree. C. and one or more dipolar aprotic solvents having a boiling point of at least about 150.degree. C., such that the solution (a) contains on a weight basis from about 5% to about 50% of the polyimide, and (b) does not undergo precipitate formation during spin coating in an atmosphere of up to about 55% relative humidity.

Abstract: A polyamideimide having an inherent viscosity of above 0.48 which comprises a unit of the following formula (II) ##STR1## and a unit of the following formula (IV) ##STR2## as main units forming the molecular chains of the polyamideimide, and an intimate mixture of the polyamideimide and a plasticising material for the polyamideimide.

Abstract: The process of the present invention includes first treating a polyamide-acid (such as LARC-TPI polyamide-acid) in an amide-containing solvent (such as N-methylpyrrolidone) with an aprotic organic base (such as triethylamine), followed by dehydrating with an organic dehydrating agent (such as acetic anhydride). The level of crystallinity in the linear aromatic polyimide so produced is maximized without any degradation in the molecular weight thereof.

Abstract: The present invention is connected with a process for preparing a novel photosensitive polyimide precursor having excellent shelf stability and high sensitivity and containing less impurities.The process for preparing a photosensitive heat-resistant polymer containing a repeating unit represented by the formula (III) comprises the step of reacting a photosensitive group-containing isoimide represented by the formula (I) with a diamine represented by the formula (II) at a temperature of 0.degree. to 100.degree. C. in the presence of a solvent: ##STR1## wherein R.sup.1 is independently a tetravalent carbon cyclic aromatic group or heterocyclic group; R.sup.2 is independently an aliphatic group having at least 2 carbon atoms, an alicyclic group, an aromatic aliphatic group, a carbon cyclic aromatic group, a heterocyclic group or a polysiloxane group; R.sup.3 is a monovalent organic group having a photosensitive unsaturated group; and D is an oxygen atom or .dbd.N--R.sup.3.

Abstract: A positively photosensitive polyimide composition is disclosed, which composition comprises polyimide having repeating unit represented by formula (I): ##STR1## wherein Ar.sup.1 represents a tetravalent aromatic hydrocarbon group; Ar.sup.2 represents a divalent aromatic hydrocarbon group having an acyloxy group at the ortho-position and/or the meta-position of the aromatic ring; Ar.sup.3 represents a divalent aromatic hydrocarbon group; and the subunit having an amount ratio of m in the repeating unit is present in an amount of at least 20% by weight based on the polyimide. The composition exhibits high photosensitivity in reproduction of a fine pattern and excellent dimensional stability.

Abstract: A polyimide resin composed essentially of repeating units represented by the general formula: ##STR1## where R is a divalent aromatic hydrocarbon radical.

Abstract: Production of polyenaminonitriles including those which can be cyclized to very stable poly(aminoquinolines) without the evolution of any small molecules and thus in a manner free of volatiles. The polyenaminonitriles are polymers which have desirable dielectric properties, and include those which can be cyclized to poly(aminoquinolines) without the evolution of volatiles to make defect-free films and composites of similar dielectric properties because of this characteristic.

Abstract: Disclosed are rigid fluorinated monomers, their preparation, and polymers derived therefrom based on two novel tricyclic xanthene core systems, 9,9-bis(perfluoroalkyl)xanthene (I) and 9-phenyl-9-perfluoroalkylxanthene (II). The monomers have utility in the preparation of advanced high-performance polymers, particularly polyimides.

Abstract: A colorless, optically clear film consisting essentially of a polyimide of the formula: ##STR1## wherein R is ##STR2## is disclosed. The composition forming the film has a weight average molecular weight, M.sub.w of at least 75,000, and has as an essential characteristic at least about 80% optical transmission at electromagnetic wavelengths of 400 nanometers and above when formed into a thickness of about two thousandths of an inch.

Abstract: A photosensitive amphiphilic high polymer comprises a linear recurring unit containing at least divalent 1st organic group (R.sup.1) having at least two carbon atoms and at least divalent 2nd organic group (R.sup.2) having at least two carbon atoms, said organic groups R.sup.1 and R.sup.2 being connected to each other by a divalent linkage group formed by a reaction of an acid group (A) containing a hetero atom and a basic group (B) containing a hetero group; and at least one hydrocarbon-containing group having 10 to 30 carbon atoms, which may have a substituent, bonded to said recurring unit by a covalent bond or an ionic bond; and a dimerizable or polymerizable unsaturated bond or an orthonitrobenzyl group ##STR1## which may have a substituent, contained in a part or the whole of said recurring unit.

Abstract: This invention relates to new fluorine-containing polyimides, polyamide-acids/esters, polyamides, addition polyimides and imide oligomers which exhibit low melting points, better solubilities, low dielectric constants, superior thermal and thermal oxidative stability, and improved processing characteristics.The products of this invention are characterized by the fact that they are derived from 4,4'-bis[2-(amino(halo)phenoxyphenyl)hexafluoroisopropyl]diphenyl ether.

Abstract: A novel composition consisting essentially of a polyimide of the formula: ##STR1## wherein R is: ##STR2## is disclosed and claimed. The composition has a weight average molecular weight, M.sub.w of at least 75,000 and a polydispersity of from about 1.8 to about 2.6.

Abstract: The invention relates to processes for preparing a polyimide, a polyimide composition prepared by the processes and polyimide composite materials containing the same.

Abstract: High temperature polymeric materials, which are easily process into void-free components, are needed for use in composites for advanced aerospace applications. These materials could bridge the gap between currently-used polymeric materials and ceramics or metal. Phthalonitrile resins can be used as high temperature polymeric material and 1,3-bis(3-aminophenoxy)benzene can be used as a curing agent to reduce voids and benzene can be used as a curing agent to reduce voids and blisters formed from volatiles during polymerization.

Abstract: Novel polyimides and co-polyimides are prepared by the condensation polymerization of an aryl diamine with dioxydiphthalic anhydride or a mixture thereof with oxydiphthalic anhydride. The polyimides and co-polyimides prepared exhibit a low moisture absorption and improved dielectric properties and can be tailored to provide a composition having desirable mechanical properties, specifically, rigidity.