Synthesis of protective coatings on steel by surface spontaneous polymerization 2. Studies of the chain propagation mechanism

We have previously reported a new method for applying protective coatings o n metal surfaces, the surface spontaneous polymerization process. Polymeriz ation occurs spontaneously on the substrate upon immersion into a monomer s olution, forming a layer of uniform coating in situ. A redox mechanism was proposed to explain the spontaneous initiation [1]. In this paper, we repor t studies of the propagation mechanism involving several monomer systems. I t was found that propagation via both a charge transfer complex and additio n of free monomers is possible, and also that both mechanisms can be operat ing at the same time. This is the case for the 4-carboxyphenyl maleimide (4 CPMI)/styrene/acrylonitrile system, in which the donor monomer, styrene, fo rms a charge transfer complex with the strong acceptor monomer, 4CPMI, and copolymerizes alternatingly while the other acceptor monomer, acrylonitrile , is incorporated randomly. The surface spontaneous polymerization process can therefore be used to copolymerize a wide variety of monomers to yield c oatings with desired properties. (C) 1998 Elsevier Science S.A. All rights reserved.