Polyimide membranes including polyimide structures selected from the group including: ##STR00001##
wherein n is an integral number where 2n100, i.e., an integer between and including 2 and 100, or an integer between 2 and 100.

The present invention provides a polyamic acid aqueous solution composition capable of polymerizing polyamic acid in water rather than in an organic solvent, as well as achieving a high imidization rate during low-temperature curing.

The present invention provides a method for manufacturing a polyimide film with a reduced gloss, which comprises providing a diamine and a diacid anhydride for polymerization in a solvent to form a polyimide precursor solution; adding 2-5 equivalents of a dehydrating agent and a catalyst into the polyimide precursor solution and then coating a carrier with the polyimide precursor solution to form a polyimide gel film; providing an embossing wheel to roll the polyimide gel film peeled from the carrier at a temperature of 140-200 C. and a pressure of 3-10 Kgf/cm.sup.2 to form a concave and convex shape on a surface of the polyimide gel film; and baking the polyimide gel film to form a polyimide film with a 60 gloss of less than 100 GUs.

One method as described herein relates to making a high molecular weight, monoesterified polyimide polymer using a small amount of bulky diamine. These high molecular weight, monoesterified polyimide polymers are useful in forming crosslinked polymer membranes with high permeance that are useful for the separation of fluid mixtures. Another method as described herein relates to making the crosslinked membranes from the high molecular weight, monoesterified polyimide polymer containing a small amount of bulky diamine. The small amount of bulky diamine allows for formation of both the high molecular weight polyimide polymer and for covalent ester crosslinks via reaction of the carboxylic acid groups with a diol crosslinking agent. This small amount of bulky diamines reduces chain mobility or segmental motion during crosslinking and reduces large loss of permeance. As such, this method provides a crosslinked membrane with good permeance and selectivity.

One method as described herein relates to making a membrane comprising an uncrosslinked high molecular weight polyimide polymer with a small amount of bulky diamine. Also as described herein is a hollow fiber polymer membrane comprising an uncrosslinked high molecular weight polyimide polymer with a small amount of bulky diamine. The polyimide polymers include monomers comprising dianhydride monomers, diamino monomers without carboxylic acid functional groups, and optionally diamino monomers with carboxylic acid functional groups, wherein 2 to 10 mole % of the diamino monomers are bulky diamino compounds and the ratio of diamino monomers with carboxylic acid functional groups to diamino monomers without carboxylic acid functional groups is 0 to 2:3. These uncrosslinked high molecular weight polyimide polymers with a small amount of bulky diamine are useful in forming polymer membranes with high permeance and good selectivity that are useful for the separation of fluid mixtures.

One method as described herein relates to making a membrane comprising an uncrosslinked high molecular weight, monoesterified polyimide polymer with a small amount of bulky diamine. These uncrosslinked high molecular weight, monoesterified polyimide polymers with a small amount of bulky diamine are useful in forming polymer membranes with high permeance and good selectivity that are useful for the separation of fluid mixtures. Also as described herein is a hollow fiber polymer membrane comprising an uncrosslinked high molecular weight, monoesterified polyimide polymer with a small amount of bulky diamine. The small amount of bulky diamine allows for formation of a membrane comprising the uncrosslinked polymer that exhibits high permeance and good selectivity.

The present invention provides a new separation functional layer suitable for separating an acid gas from a gas mixture containing the acid gas. A separation functional layer of the present invention includes polyimide. The polyimide includes a structural unit A1 derived from a tetracarboxylic dianhydride having a six-membered ring acid anhydride structure, and a structural unit B1 derived from diamine. At least one of the structural unit A1 and the structural unit B1 has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, a thiol group, and metal salts of these groups.

A method for using citraconic anhydride and itaconic anhydride as addition cure end caps in reactions for forming polyamic acid oligomers and polyimide oligomers, is provided. Prepregs and high temperature adhesives made from the resulting oligomers, as well as, high temperature, low void volume composites made from the prepregs, are also provided.

A method for producing a polyimide precursor, including: reacting tetracarboxylic dianhydride represented by the following General Formula (1) with a diamine compound represented by the following General Formula (2) in a compressive fluid to thereby produce a polyimide precursor represented by the following Formula (3): ##STR00001## where, X in the General Formulae (1) and (3) denotes a tetravalent aromatic group or a tetravalent alicyclic group, Y in the General Formulae (2) and (3) denotes a divalent organic group, and n denotes the number of repetitions.

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.