Poly(N-isopropylacrylamide) and poly(2-(dimethylamino)ethyl methacrylate) grafted on an ordered mesoporous silica surface using atom transfer radical polymerization with activators regenerated by electron transfer

Abstract

Atom transfer radical polymerization with activators regenerated by electron transfer was demonstrated as a convenient strategy to graft functional polymers from a concave surface of ordered mesoporous silica. SBA-15 silica with cylindrical mesopores of diameter 24 nm (nominal BJH pore diameter of 29 nm) was used as a support, and poly(N-isopropylacrylamide) (PNIPAAm) as well as poly(2-(dimethylamino)ethyl methacrylate) as grafted polymers, which are known for their stimuli-responsive properties. Successful polymerizations were performed in small vials without prior deoxygenation. The resulting silica/polymer composites had appreciable specific surface areas of 68–145 m² g⁻¹ and accessible pores of nominal (BJH) diameters 21–24 nm, with up to 26 wt% polymer loading. PNIPAAm chains cleaved from the silica support had a quite low polydispersity index (∼1.26) throughout the grafting process. Temperature-responsive properties of the silica/PNIPAAm composite were confirmed by using differential scanning calorimetry.