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

Abstract

We have previously reported a new method for applying protective coatings on metal surfaces, the Surface Spontaneous Polymerization Process (1). In this process, polymerization occurs spontaneously on the substrate upon immersion into a monomer solution, forming a layer of uniform coating in-situ. No initiator is added. In this paper, studies on the development of the process and coating properties are reported. A monomer reaction system containing phenylmaleimide/styrene/bismaleimide/2-(methacryloyoxy)ethyl acetoacetate has been developed to afford protective coatings on steel. The coatings obtained from this system have good thermal, dielectric, and adhesion properties. Corrosion resistance of 4CPMI coatings, as measured by the ASTM B-117 salt spray test, is excellent after 700 hours of salt spray. The effects of several process variables on the polymer molecular weight were also studied, including monomer concentration, solution temperature, solution pH, and monomer feed composition. Solution stability studies indicate that polymerization occurs only on the surface and does not propagate into the solution.