Preparation and carbon dioxide separation membrane of the carbon dioxide separation membrane

The invention, selectively high affinity substituent has the introduced graft chains against carbon dioxide, to provide a carbon dioxide separation membrane having a high carbon dioxide separation performance. The present invention is a radiation process (1) for irradiating the polymer film; process the polymer film wherein the radiation is irradiated, to form a graft chain a repeating unit of a monomer having fluoride ions and salifiable substituent (2); and wherein the fluoride ion and salt formation possible substituents by treatment with a fluoride salt, the production of carbon dioxide separation membrane comprising a step (3) to form salts with fluoride ions in the substituents it is a method.