SOLUBLE AROMATIC RANDOM COPOLYIMIDE AND PROCESS FOR PREPARING SAME

A soluble aromatic random copolyimide and a process for preparing same are herein disclosed, wherein the copolyimide is prepared from (a) an aromatic diamine and two or more different aromatic dianhydrides or (b) an aromatic dianhydride and two or mo re different aromatic diamines; wherein at least one of the diamine or the dianhydride contains a sulfonyl group directly or indirectly linking the two amine moieties in said diamine or the two anhydride moieties in said dianhydride. The copolyimide is soluble at room temperature in polar organic solvents such as N-methyl-2-pyrollidone, N,N-dimethylacetamide, and dimethylformamide, and has a glass transition temperatures below its respective melting points. As such, the copolyimide is more easily solubilized and processed into working forms, while still retaining desirable characteristics such as heat resistance, and may be used in various applications for which aromatic polyimides are known to be useful.