Thermal imidization of poly(amic acid) precursors on glycidyl methacrylate (GMA) graft-polymerized Si(100) surface

Abstract

A novel method was developed to achieve good adhesion of polyimides (PI) on Si(100) surface via thermal imidization of the poly(amic acid) precursors of poly(pyromellitic dianhydride-co-4,4′-oxydianiline) onto an argon plasma-pretreated and glycidyl methacrylate (GMA) graft-polymerized Si(100) (GMA-g-Si) surface. The laminate showed a 180°-peel adhesion strength of approximately 8.0 N/cm, compared to negligible adhesion strength for the laminates prepared from thermal imidization of the poly(amic acid) on pristine and argon plasma-treated Si(100) substrates. The high adhesion strength was attributed to the synergistic effect of coupling the curing of epoxide functional groups of the grafted GMA chains with the imidization process of the poly(amic acid) and the fact that the GMA chains were covalently tethered on the Si(100) surface. The reactions and composition at the interphase were investigated by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The plasma-activated and graft-modified silicon surfaces were characterized by XPS and atomic force microscopy. XPS results also revealed that the PI/GMA-g-Si assembly was delaminated by cohesive failure inside the PI film.