Preparation of ultra-thin freestanding polyimide films with sequential evaporation technique

Ultra-thin freestanding polyimide(PI) films of 100 nm thickness were formed by sequential evaporation of 4,4'-diaminodiphenyl ether(ODA) and pyromellitic dianhydride(PMDA) precursor monomers followed by a thermal treatment of 150 ℃ 1 h and 350 ℃ 2 h.The chemical structures of the PI films were investigated using FTIR spectroscopy and the degree of imidization was calculated.Results show that the PI film has a fully imidization.The surface morphology of the films,compared with co-deposited PI films,was observed using AFM,the surface morphology of the PI films would be better by depositing ODA first.