ABSTRACT This study prepared PI/PTFE (polyimide/polyfluoroethylene) bilayer composite films. Firstly, the inert surface of the PI film was modified using chemical wet acid etching. Subsequently, PTFE latex and FEP latex were blended and applied onto the modified PI film through a coating–drying–sintering process to form the bilayer composite film. The film formation and modification mechanism were investigated, and comprehensive analysis was conducted on the surface morphology, thermal properties, crystallinity properties, and mechanical properties of the composite film samples. Contact angle measurements and SEM results demonstrated that acid‐etched wet treatment effectively enhanced the surface roughness of the PI film, improving latex film formation. FT‐IR confirmed the chemical structural stability of the blended PTFE/FEP (fluorinated ethylene propylene) alloy coating after thermal treatment. Cross‐sectional SEM and mechanical testing revealed reliable adhesion between the blended coating and the modified PI substrate. DSC and GI‐XRD studies elucidated FEP's influence on coating crystallinity. Subsequent in situ POM analysis revealed that FEP, acting as a filler, improved PTFE flowability and reduced stress relaxation, transforming the coating surface from convex to concave. This topographical change was confirmed by SEM characterization and further validated by peel test results.
Shen et al. (Tue,) studied this question.