Surface-functionalized polyaniline films

Abstract

The surfaces of emeraldine (EM) base films of polyaniline (PANi) have been functionalized by thermal graft copolymerization with acrylic acid (AAc) and N,N-dimethyl(methacryloylethyl)ammonium propanesulfonate (DMAPS). The AAc graft copolymerized EM films were further functionalized via covalent immobilization of glucose oxidase (GOD) and collagen. The so-immobilized GOD still retains a substantial amount of activity. The amphoteric DMAPS graft copolymerized EM base films are capable of exhibiting strong adhesive-free adhesion to one another and to another similarly modified dielectric film, such as a surface graft copolymerized poly(tetrafluoroethylene) (PTFE) film. Lap shear adhesion strengths on the order of 300 and 100 N/cm2 were obtained for the respective cases. Pristine PANi films of various intrinsic oxidation states are capable of undergoing spontaneous surface metallization through reduction of precious metal ions, such as gold and palladium, in acid solutions to their elemental forms. The rate of metal reduction is favored by a low intrinsic oxidation state of the polymer. The surface composition and microstructure of the polymer films after modification, functionalization, and metallization were characterized by angle-resolved X-ray photoelectron spectroscopy (XPS).