Polyimide(PI) is one of the high-performance polymers widely used in many high-tech fields

including high temperature materials in the aviation and aerospace fields

flexible displays

solar cells and microelectronics manufacturing and so on. But polyimide is low in solubility in most organic solvents and can only be dissolved in a few high boiling polar organic solvents

which leads to the difficulty of the traditional polyimide processing and restricts its application. Therefore

it is particularly important to improve the solubility of polyimide for the realization of the low cost of polyimide. In this paper

the research progress on polyimide solubility in recent years is mainly summarized

including the introduction of aliphatic groups

bulky triaryl imidazole units

the introduction of halogenated units

copolymerizaion and other methods

and their properties of solubility are described.