This invention relates to a polyamide-imide precursor, a polyamide-imide obtained by imidizing the same, a polyamide-imide film, and an image display device including the film. The polyamide-imide precursor includes, in a molecular structure thereof, a first block, obtained by copolymerizing monomers including dianhydride and diamine, and a second block, obtained by copolymerizing monomers including an aromatic dicarbonyl compound and aromatic diamine. The dianhydride includes biphenyltetracarboxylic acid dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), and the diamine includes bistrifluoromethylbenzidine (TFDB).

A poly(amide-imide) copolymer that is a reaction product of a diamine represented by Chemical Formula 1, a diamine represented by Chemical Formula 2, a dicarbonyl compound represented by Chemical Formula 3, and a tetracarboxylic acid dianhydride represented by Chemical Formula 4, a composition for preparing the poly(amide-imide copolymer, and an article including the copolymer, e.g., a film are provided:

##STR00001## wherein, in Chemical Formulae 1 to 4, R.sup.a, L.sup.1, L.sup.2, n1, A, R.sup.3, X, R.sup.10, R.sup.12, R.sup.13, n7 and n8 are the same as defined in the specification.

The invention relates to a process for producing an aromatic polyimide, comprising the following steps: (a) preparing one or more salt(s) by reacting one or more aromatic tetracarboxylic acid(s) in the solid state and one or more diamine(s), optionally in the presence of one or more chain limiter(s), in the presence of one or more binder(s), comprising one or more organic liquid(s), in an amount of from 1% to 25% by weight relative to the total weight of the aromatic tetracarboxylic acid(s), of the diamine(s) and of the optional chain limiter(s), then; (b) polymerising the salt(s) obtained in step (a).

An aqueous solvent solution of an imide group-containing compound which contains an imide group-containing compound produced by partial hydrolysis of a polyimide molded article is provided.

Provided are an aqueous solvent solution of an imide group-containing compound and a method for producing the same including steps of: (1) preparing a polyimide molded article by cutting the polyimide molded article into a predetermined size, (2) hydrolyzing the polyimide molded article at temperature conditions of 50 to 100 C. in the presence of water and a basic compound to have a crude imide group-containing compound in solution state, (3) purifying the crude imide group-containing compound in solution state to have an imide group-containing compound in semi-solid state, and (4) dissolving the imide group-containing compound in semi-solid state, an aqueous solvent, and a predetermined alkali compound to have a predetermined aqueous solvent solution.

A salt composition includes at least one ammonium carboxylate salt obtained from: (a) at least one aromatic compound comprising 2 anhydride functional groups and/or its carboxylic acid and/or ester derivatives; and (b) one or more aliphatic diamines in which said aliphatic diamine or diamines are chosen from the diamines of formula (I) NH.sub.2RNH.sub.2 with R being a saturated aliphatic divalent hydrocarbon radical, the two amine functional groups of which are separated by 4 to 6 carbon atoms and 1 or 2 hydrogen atoms of the divalent radical of which are replaced by 1 or 2 methyl and/or ethyl groups; and optionally the diamines of formula (II) NH.sub.2RNH.sub.2 with R being a saturated or unsaturated and aliphatic, cycloaliphatic or arylaliphatic divalent hydrocarbon radical, which optionally comprises heteroatoms; and at least one chain-limiting compound chosen from monoamines, monoacids or diacids in the , positions.

A polyetherimide of improved color and processes for preparing the polyetherimide are disclosed.

The present invention relates to a pickering emulsion composition using polyimide particles and a method for preparing the same. The pickering emulsion stabilized by the polyimide particles according to the present invention has a very stable dispersed phase and does not cause flocculation, creaming, coalescence and phase separation even after a long time, and has an advantage of being capable of forming both an oil-in-water type emulsion and a water-in-oil type emulsion. Further, the polyimide particles used in the present invention can be synthesized in a simple manner and have partial wettability without the surface treatment and pH control so that they can be easily used for the emulsion stabilization.

The present invention discloses a modified bismaleimide resin and preparation method thereof; under conditions of N,N-dimethylformamide serving as a catalyst, biomass-based 2,5-furandicarboxylic acid and thionyl chloride are acylated to obtain 2,5-furan diformyl chloride, which is then dissolved in dichloromethane with a biomass-based eugenol; under tertiary amine conditions an esterification reaction takes place, and a fully biomass-based bis(4-allyl-2-methoxyphenyl)furan-2,5-dicarboxylic acid ester is thus obtained; same is used for preparing a modified bismaleimide resin. The bismaleimide resin prepared by the present invention has excellent thermal properties and rigidity; the preparation method uses 2,5-furandicarboxylic acid from biomass as well as eugenol; the raw materials are green and environmentally friendly and renewable; the invention also has the feature of a simple production process, and has broad prospects for application in such fields as aeronautics and astronautics, electronic information, electrical insulation.

A polyimide precursor solution is provided. The polyimide precursor solution includes 100 parts by weight of a fully aromatic polyamic acid, 5-20 parts by weight of silica particles, 10-40 parts by weight of an alkoxysilane, and 60-80 parts by weight of a solvent.

A solvothermal synthesis process for polyimides is provided. The process uses solution polymerization of monomers in an appropriate solvent, by mixing the solvent and the monomers and heating the mixture under pressure at temperatures exceeding the respective boiling point at normal pressure. The process produces essentially completely crystalline polyimides by a) mixing and heating the solvent and the monomers by either (i) heating the solvent up to solvothermal conditions and subsequently adding the monomers to initiate the reaction, or (ii) mixing the monomers with the solvent and heating the mixture up to solvothermal conditions within a period of 5 min, the reaction temperature TR being held below the solid-state polymerization temperature TP of the monomers during the polymerization; and b) carrying out the solution polymerization until essentially complete conversion is achieved.