The invention relates to a stoichiometric salt of a tetracarboxylic acid and a diamine of the following general formula (I),

##STR00001##

wherein R.sub.1 is selected from tetravalent residues of butane, cyclobutane, cyclopentane, cyclohexane, tetrahydrofurane and benzophenone and R.sub.2 is selected from divalent residues of unbranched, branched or cyclic aliphatic hydrocarbons with 3 to 15 carbon atoms, with the proviso that the salt of the formula (I) is water-soluble and is selected from compounds (1) to (28); and to the polyimides prepared from these salts by polycondensation.

A polyimide film with improved dielectric and mechanical properties includes a polyimide layer with a liquid crystal structure which incorporates liquid crystal polymer powder. The polyimide layer is formed by a condensation reaction applied to dianhydride and diamine monomers, at least one of the dianhydride monomer and the diamine monomer having the liquid crystal structure. A method for manufacturing the polyimide film is also disclosed.

A method for producing a reactive intermediate composition, including: reacting a substituted phthalic anhydride of the formula (I) with a diamine of the formula H.sub.2N—R—NH.sub.2 in the presence of an aromatic dianhydride in an amount of 10 to 50 mole percent based on the total moles of anhydride functionality in the reaction; wherein the reacting is conducted in an aprotic solvent in a reactor, under conditions effective to produce the reactive intermediate composition; and wherein X comprises a halogen or a nitro group, and R comprises a C.sub.6-36 aromatic hydrocarbon group or a halogenated derivative thereof, a straight or branched chain C.sub.2-20 alkylene or a halogenated derivative thereof, or a C.sub.3-8 cycloalkylene or a halogenated derivative thereof. ##STR00001##

The present disclosure describes methods of polyimide synthesis and polyimides made therefore. The method includes placing a tetracarboxylic compound and a solvent in a reaction vessel and adding a first amount of a diamine. The first amount of the diamine is not more than 99.5 mol % of the tetracarboxylic compound inside the reaction vessel. The method can include agitating the mixture and determining a viscosity of the mixture. The method can further include adding a second amount of the diamine. The last steps can be repeated until the viscosity increases to a target value. The target viscosity can be correlated to a peak weight-averaged molecular weight of the polyimide.

A dual-cure method for forming a solid polymeric structure is provided. An end-capped, imide-terminated prepolymer is combined with at least one photopolymerizable olefinic monomer, at least one photoinitiator, and a diamine, to form a curable resin composition, which, in a first step, is irradiated under conditions effective to polymerize the at least one olefinic monomer, thus forming a scaffold composed of the prepolymer and the polyolefin with the diamine trapped therein. The irradiated composition is then thermally treated at a temperature effective to cause a transimidization reaction to occur between the prepolymer and the diamine, thereby releasing the end caps of the prepolymer and providing the solid polymeric structure. A curable resin composition comprising an end-capped, imide-terminated prepolymer, at least one photopolymerizable olefinic monomer, at least one photoinitiator, and a diamine, is also provided, as are related methods of use.

A photosensitive polyimide resin for ultraviolet curing-based three-dimensional printing, which is prepared from 40-60 parts by weight of an active group-containing polyimide resin; 20-50 parts by weight of an organic activator; and 2-5 parts by weight of a photoinitiator. This application further provides a method for preparing the photosensitive polyimide resin.

Embodiments relate to a polymer film that is excellent in folding characteristics and transparency and maintains excellent mechanical properties even after repeated elongation and shrinkage in the elastic region, a process for preparing the same, and a front panel and a display device comprising the same. The polymer film comprises a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin and has an MOR.sub.0/9 of Equation A of 2% or less.

A method for manufacturing a thick polyimide film includes providing a first and second laminated structures. The first and second laminated structures are heated, and the heated first and second laminated structures are wound together to form a third laminated structure. The first polyamic acid gel film of the heated first laminated structure and the second polyamic acid gel film of the heated second laminated structure are overlapped and bonded together to form a third polyamic acid gel film. Two third laminated structures are wound together to form a fourth polyamic acid gel film. A dehydration ring-closure imidization reaction is applied to the fourth polyamic acid gel film by heating to obtain the thick polyimide film. A thick polyimide film manufactured by the method is also disclosed.

This invention provides a cell culture substrate comprising on its surface a fluorine-containing polymer that enables three-dimensional tissue culture. The cell culture substrate of the invention has a surface at least a part of which is composed of a resin composition comprising a fluorine-containing polymer having one or more fluorine atoms in a repeating unit and exhibits the oxygen gas permeability of 219 cm.sup.3 (STP)/(m.sup.2.Math.24 h.Math.atm) or higher. Three-dimensional tissue can be formed via cell culture with the use of the cell culture substrate of the invention.

Provided are an imide-terminated prepolymer, a preparation method therefor, a curable resin composition, use thereof and a dual curing method. An end capped, imide-terminated prepolymer is mixed with at least one photopolymerizable ethylenic monomer, at least one photoinitiator and diamine, and optionally a pigment to form a curable resin composition, which, in a first step, is irradiated under conditions effective to polymerize the at least one ethylenic monomer. The irradiated composition is then heat-treated under conditions effective to cause a transimidation reaction between the prepolymer and the diamine to provide a solid polymer.