Disclosed is a polyamic acid having Formula I

##STR00001##

In Formula I: R.sup.a represents one or more different tetracarboxylic acid component residues; R.sup.b represents one or more different aromatic diamine residues or aromatic diisocyanate residues; and 5-100 mol % of R.sup.b has Formula II

##STR00002##

In Formula II: R.sup.1 through R.sup.6 are the same or different and are haloalkyl or haloalkoxy; R.sup.7 is the same or different at each occurrence and is deuterium, halogen, cyano, hydroxyl, alkyl, deuterated alkyl, heteroalkyl, alkoxy, heteroalkoxy, haloalkyl, haloalkoxy, silyl, siloxy, hydrocarbon aryl, substituted hydrocarbon aryl, heteroaryl, substituted heteroaryl, vinyl, or allyl; n is an integer from 0-10; x1 and x4 are the same or different and are an integer from 0-3; x2 and x3 are the same or different and are an integer from 0-2; and * indicates a point of attachment.

A hydrophobic polyimide material and a preparation method thereof, and an organic electroluminescence light emitting diode are provided. The hydrophobic polyimide material includes organic/inorganic composite nanoparticles. The preparation method of the hydrophobic polyimide material includes steps: mixing polyamic acid solution and organic/inorganic composite nanoparticle solution evenly, and stirring to obtain solution of the hydrophobic polyimide material; coating the solution of the hydrophobic polyimide material on a surface of a substrate to obtain hydrophobic polyimide by baking and curing.

A poly(amide-imide) is provided. The poly(amide-imide) is represented by formula (1), ##STR00001## wherein R is a C.sub.6 aryl group, a C.sub.7-C.sub.8 aralkyl group, a C.sub.2-C.sub.6 alkoxyalkyl group, or a C.sub.3-C.sub.18 alkyl group; and 0.02≤X≤0.5.

Provided are a polyimide-based film, a window cover film, and a display panel including the same. More particularly, a polyimide-based film having excellent visibility, a window cover film using the same, and a display panel including the same are provided.

A polyimide precursor composition according to the present invention enables alleviation of thermal expansion-contraction properties of a polyimide film resultingly prepared, by means of using siloxane-based diamine having a particular structure and a solvent having a positive partition coefficient. And the present invention enables excellent transparency, heat resistance, mechanical strength and flexibility and effective reduction of residual stress, and thus can be used in various fields such as a substrate for a device, a cover substrate for a display, an optical film, an integrated circuit (IC) package, an adhesive film, a multi-layer flexible printed circuit (FPC), tape, a touch panel and a protective film for an optical disk.

An air-permeable filter material that includes a polymeric aerogel having a polymeric matrix comprising an open-cell structure is disclosed. The air-permeable filter material can be included in a mask, which can be configured to be placed over a user's mouth and/or nose. The mask can include at least one layer of the air-permeable filter material and is positioned such that inhaled and/or exhaled air of the user passes through the filter material.

A polyimide-based composition includes a polyimide precursor and a solvent, in which the polyimide precursor includes repeating units represented by Chemical Formula 1 to 3. A polyimide film is also made from the composition.

##STR00001##

A polyimide-forming composition includes a polyimide prepolymer, an amine, and a solvent comprising a C.sub.1-6 alcohol. A method of manufacturing the polyimide-forming composition is disclosed. The method includes heating a substituted or unsubstituted C.sub.4-40 bisanhydride in a C.sub.1-6 alcohol to dissolve the bisanhydride, adding a substituted or unsubstituted divalent C.sub.1-20 diamine to form a polyimide prepolymer, and adding the amine in an amount effective to solubilize the polyimide prepolymer in the C.sub.1-6 alcohol, in a solution of the C.sub.1-6 alcohol and deionized water, or in deionized water. A method of manufacturing an article including a polyimide is also disclosed.

A particle-dispersed polyimide precursor solution contains: a polyimide precursor consisting of a polymer of a tetracarboxylic dianhydride and a diamine containing a fluorene-based diamine having a fluorene skeleton; particles; and an aqueous solvent containing water.

Disclosed are a polyamideimide resin composition comprising (A) a polyamideimide resin, (B) a 3-alkoxy-N,N-dimethylpropanamide, and (C) water; and a fluorine-based coating material comprising the polyamideimide resin composition and a fluororesin.