Thermal imidization of poly(pyromellitic dianhydride-4, 4'-oxydianiline) precursors on fluoropolymers modified by surface graft-copolymerization with glycidyl methacrylate

摘要

Composite films of polyimide (PI) and poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) or of PI and poly(tetrafluoroethylene) (PTFE) were prepared by thermal imidization of the poly(amic acid) (PAA) precursors of poly(pyromellitic dianhydride-4,4'-oxydianiline) (PMPA-ODA) on glycidyl metharylate (GMA) graft-copolymerized FEP and PTFE films. The resulting PI/GMA-g-FEP and PI/GMA-g-PTFE composites exhibited T-peel adhesion strength of approximately 7.0 and 6.5 N/cm. respectively, compared to negligible adhesion strength for the laminates prepared from thermal imidization of the PAA on the pristine and the Ar plasma-treated FEP and PTFE films. X-ray photoelectron spectroscopy (XPS) results revealed that both the PI/GMA-g-FEP and PI/FEP-g-PTFE composite films determinated by cohesive failure inside the FEP and PTFE films, respectively. The so-delaminated Pi films with a covalently tethered FEP or PTFE surface layer were highly hydrophobic, having static water contact angles above 140 deg C. The highly hydrophobic property depends on both the composition and roughness of the delaminated surface.