Synthesis of protective coatings on steel by surface spontaneous polymerization. 3: Process development and coating property studies

We have previously reported a new method for applying protective coatings o n metal surfaces, the Surface Spontaneous Polymerization Process (1). In th is process, polymerization occurs spontaneously on the substrate upon immer sion into a monomer solution, forming a layer of uniform coating in-situ. N o initiator is added. In this paper, studies on the development of the proc ess and coating properties are reported. A monomer reaction system containi ng phenylmaieimide/styrene/bismaleimide/2-(methacryloyoxy) ethyl acetoaceta te has been developed to afford protective coatings on steel. The coatings obtained from this system have good thermal, dielectric, and adhesion prope rties. Corrosion resistance of 4CPMI coatings, as measured by the ASTM B-11 7 salt spray test, is excellent after 700 hours of salt spray. The effects of several process variables on the polymer molecular weight were also stud ied, including monomer concentration, solution temperature, solution pH, an d monomer feed composition. Solution stability studies indicate that polyme rization occurs only on the surface and does not propagate into the solutio n.