N-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazole-1-ethyl]-2-bromoisobutyramide as initiator for atom transfer radical polymerization (ATRP) and surface-initiated ATRP of methyl methacrylate on iron

Abstract

N-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazole-1-ethyl]-2-bromoisobutyramide (IEB) was synthesized and characterized by elemental analysis, FT-IR, and 1H NMR. It had been successfully used as a bidentate initiator for the ATRP of methyl methacrylate with CuBr/2,2′-bipyridine as the catalyst, and N,N-dimethylformamide as the solvent at 70 °C. The kinetics was first order in monomer and the number-average molecular weight of the polymer increased linearly with the monomer conversion, indicating the ‘living’/controlled nature of the polymerization. The polymerization reached high conversions producing polymers with a low molecular weight distribution (Mw/Mn = 1.319). The obtained poly(methylmethacrylate) (PMMA) functionalized with 2-(8-heptadecenyl)-4,5-dihydro-1H-imidazoleyl and ω-Br as the end groups were characterized by FT-IR spectroscopy. They can be used as macroinitiators for chain extension reaction. Then, PMMA coatings were grafted from iron substrates by surface-initiated ATRP from a surface-bound IEB initiator. The EIS measurements confirmed the successful grafting of the polymer coatings. Greatly improved short-term anticorrosive properties for PMMA-modified electrodes were demonstrated by substantially increased resistance of the film for a period of 24 h as compared to bare iron.