Grafting of polymer brushes from nanopore surface via atom transfer radical polymerization with activators regenerated by electron transfer

Abstract

It is shown that atom transfer radical polymerization (ATRP) with activators regenerated by electron transfer (ARGET) is a powerful approach for grafting of polymer brushes from surfaces of high-surface-area nanoporous hosts, allowing one to achieve controlled polymer loadings and film thicknesses while maintaining the pore accessibility and moderate or high surface area. The approach was illustrated on SBA-15 silicas with cylindrical pores of diameter 22 and 14 nm as the nanoporous supports, and poly(methyl methacrylate) (PMMA) and polystyrene (PS) as the grafted polymers. The polymer loadings up to 36 wt.% and the grafted layer thicknesses of up to at least 2 nm were achieved in the polymerization process carried out in small vials without using a vacuum line. The specific surface areas of the obtained silica-polymer composites were 60–190 m² g⁻¹. The polymer chains exhibited quite low polydispersity (1.18–1.32) for polymer loadings up to 29 wt.%, while a higher polydispersity was observed for higher loadings, in which case the pores of the support were filled to a significant extent with the polymer graft. Due to its simplicity, ARGET ATRP emerges as a powerful and yet surprisingly straightforward way to synthesize well-defined polymer brushes in nanopores, opening a convenient avenue to a wide range of porous high-surface-area silica-polymer composites.