Corrosion protection of iron surface modified by poly(methyl methacrylate) using surface-initiated atom transfer radical polymerization (SI-ATRP)

A new N-heterocyclic initiator N-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazole-1-ethyl]-2-bromoisobutyramide was synthesized and immobilized on the surface of iron. Methyl methacrylate was grafted from iron substrates via surface-initiated atom transfer radical polymerization (ATRP). The first-order kinetics of poly(methyl methacrylate) (PMMA) grafting from iron revealed the control of ATRP throughout the reaction, and the polymerization reached a high conversion producing polymers with good control of molecular weights (M _n = 68,800) and low polydispersity indexes (M _w/M _n < 1.32). The thickness of the polymer brush films was greater than 47 nm after 7 h of reaction time. The grafting density was estimated to be 0.48 chains nm⁻². The iron surfaces at various stages of modification were characterized by scanning electron microscopy and energy dispersive spectrometer. The analytical results were consistent with a thin compact polymer coating on the surface of iron. Iron surface with grafted PMMA coating showed significant corrosion resistance. This work demonstrated that the surface-initiated ATRP is a versatile means of the surface modification of active metals with well-defined and functionalized polymer brushes.