Grafting of bisphenol-A polycarbonate and polymethyl methacrylate on to the surface of carbon fibers via anionic polymerization

Formation of a covalently bonded interface via polymer grafting should be a very useful technique to improve interfacial adhesion between carbon fiber surfaces with otherwise unreactive thermoplastic resins in composite materials. In this study, we have grafted bisphenol-A polycarbonate and polymethyl methacrylate on to the surface of polyacrylonitrile based carbon fibers via anionic polymerization. The reaction of the fiber surface with butyl lithium in the presence of N,N,N,N'-tetramethyl ethylene diamine and 18-crown-6 crown ether was found to be the most effective method to produce highly active metallized aromatic groups capable of initiating anionic polymerization. The grafting of polycarbonate on to the surface proceeded via a ring opening polymerization of cyclic oligocarbonates, while polymethyl methacrylate was formed through the consumption of methyl methacrylate monomer. The grafting on the surface of the fiber was confirmed using X-ray photoelectron spectroscopy and electron microscopy. The degree of polymerization of polycarbonate was found to be low, while that of polymethyl methacrylate was high.