Characteristics and electrical properties of polyimide films fluorinated for different durations

Abstract

Surface fluorination of polyimide films was conducted for different durations (30, 60, and 90 min) in a laboratory vessel using an F2/N2 gas mixture containing 12.5 % F2 by volume. The differences in the structural, morphology, wettability, surface free energy, and electrical properties of the fluorinated polyimide films were systematically studied to assess the effects of fluorination and fluorination time, and to investigate the relationship between the surface electrical properties and surface physicochemical properties. The obtained results indicated that fluorination cracked the film surface, with the number of cracks increasing with increasing fluorination time. Fluorination also enhanced the surface wettability and polarity. Surface conductivity and surface potential decay measurements consistently showed that the surface-fluorinated samples had a higher surface conductivity than unfluorinated samples, and that the surface potential rapidly decayed because the surface conductivity increased with enhanced water adsorption on the surface. The increased occurrence of surface cracks, as well as enhanced polarity and surface conductivity of the films, were mainly attributed to the increase in the degree of chain scission that occurred with increasing fluorination time.