The accelerated CO2 plasticization of ultra-thin polyimide films and the effect of surface chemical cross-linking on plasticization and physical aging

For the first time, the permeation experiments of CO2 are carried out on ultra-thin dense polyimide films (0.5–1.8 μm). The observation of accelerated CO2 plasticization indicates that the conventionally defined “plasticization pressure” as an inherent material properties measured from thick dense films is strongly thickness dependent. This accelerated plasticization phenomenon observed in ultra-thin dense films is probably attributed to two factors: (1) the swelling and softening effects of the sorbing CO2 molecules on the polymer chains; and (2) weak micro-mechanical properties and less sorption capacity of ultra-thin films to accommodate the sorbed CO2 molecules. Experimental results suggest that chemically modified ultra-thin films show characteristics of retarded aging process and significantly suppressed plasticization.