Although polymer membranes have been developed for a long time, it is still after the 20th century to study them systematically. With the development of petroleum industry, there are plastic films, but mainly used as packaging materials, almost no function. Cellulose membrane has been used in ultrafiltration separation since 1930s. It was not until 1940s that the development and utilization of ion exchange membrane and the research and development of electrodialysis separation method were developed. The experimental and theoretical research of reverse osmosis membrane separation technology was not initiated until the early 1950s by Canadian scholar 5. Suririajan. In 1860, soliragin and 5. Loed successfully produced the first membrane separation technology A high-performance membrane has laid a foundation for the reverse osmosis method for seawater purification. In 1961, a.s.michael, an American scholar, successfully prepared a practical ultrafiltration membrane. Since then, the polymer functional membrane technology has developed rapidly. According to the statistics of Japan, there are more than 20 or 50 patents about the materials, devices and methods of separation membranes in the past 10 years. In addition, more than 100 academic papers are published every year in the plastic film Research Association of Japan polymer society or in the journal "membrane" of Japan membrane society. Among the polymer functional membranes, the most widely used one is selective permeation separation membrane, including dialysis membrane, ion exchange membrane, reverse osmosis membrane, microporous filtration membrane, ultrafiltration membrane, gas and liquid separation membrane, liquid membrane, kinetic membrane, biomedical membrane, etc. Various types of separation membranes have been widely used in nuclear fuel and metal refining, gas and hydrocarbon separation, seawater and brackish water desalination, preparation of pure water and ultra pure water, environmental protection and sewage treatment, artificial organ manufacturing, purification of biological products, medicine, food, agriculture, chemical industry and so on 。 Membrane separation is considered to be a promising material separation method with low energy consumption and high efficiency. The application of functional polymer membrane materials may greatly save energy and realize pollution-free clean chemical industrial production. In the ten-year research and development plan of high-performance polymer materials in Japan from 1981 to 1990, high-efficiency polymer separation membrane is listed as one of the three key topics. According to a report of an American company, the total sales volume of functional membranes in the world is estimated to be about 1.8 billion US dollars in 1990, which is six times higher than that in 1892. In addition, it is predicted that the 20 and 30 intestines of boilers in the world will be equipped with membrane oxygen enrichment devices in 1900, and the membrane separation of organic solution (especially azeotrope) will be practical and replace the distillation process. In a word, the development prospect of functional polymer membrane materials is very broad.http://www.china-polyimide.com