Polyimide (PI) can be made into films

fibers

foams and has been widely applied in many high-tech fields such as aerospace

liquid crystal display

microelectronics and so on. Among them

the application of PI films is particularly extensive. In the process of preparing PI films from solution

it is very important to control the chain structure of polyimide in the solution which further influences the condensed structure and the properties of the films. Therefore

it is necessary to study the properties of polyimide solutions. The properties of polymer solution include the conformation and flexibility of polymer chain in solution

the molecular parameters related to the chain conformation and their scaling relationships

and the factors affecting the chain conformation. In this paper

recent progress on the solution properties of soluble polyimide was summarized including the chain conformation

basic molecular parameters and their scaling relationships

the effects of structural factors and external conditions (temperature

etc.

) on the chain flexibility of some soluble polyimides in different solvents. The future development of the research on the solution properties of soluble polyimide is also proposed.