Polyimide copolymers have random copolymers, alternating copolymers and block copolymers. If the polymer is synthesized by the A-A and B-B type monomers, copolyimide refers to two or more dianhydrides with one or more diamines. Or of two or more diamines with one or more of a polymer obtained by polycondensation of dianhydrides. Macromolecular chain distribution of the various components is disordered compared to a random copolymer. If different components are compared with the strict and orderly arranged in alternating copolymer macromolecular chains. So far reported copolyimides the vast majority belong to the former and less of the latter example. There are different structures in the form of polymer segments distributed in the macromolecular chain compared with the block copolymer. Random copolymers follow the general characteristics of the copolymer in the synthesis nor special.