Surface Structures and Adhesive-Free Adhesion Characteristics of Polyaniline Films after Modification by Graft Copolymerization

Abstract

Surface modifications of emeraldine base (EB) films have been carried out via thermally induced graft copolymerization with acrylic acid (AAc), sodium salt of styrenesulfonic acid (NaSS), N,N‘-dimethyl(methacryloylethyl)ammonium propanesulfonate (DMAPS), and acrylamide (AAm). The structure and chemical composition of each graft-copolymerized surface were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). In all cases, the concentration of grafting increases with monomer concentration. Surface grafting with the four functional monomers also leads to a more hydrophilic EB film surface. Two graft-copolymerized EB film surfaces are capable of exhibiting adhesive-free adhesion when brought into direct contact in the presence of water and subsequently dried. This adhesive-free adhesion also exists between a surface-modified EB film and a similarly modified polytetrafluoroethylene (PTFE) film from graft copolymerization. The development of the lap shear adhesion strength depends on the concentrati...