Silica/poly (N-vinylimidazolium) nanospheres by combined RAFT polymerization and thiol-ene click chemistry

We report a facile method that combined sol-gel reaction, reversible addition-fragmentation chain transfer (RAFT)/macromolecular design via interchange of the xanthates process and thiol-ene click reaction to prepare monodisperse silica core-poly(N-vinylimidazole) (PVim) shell microspheres of 200 nm in average diameters. First, silica with C = C double bonds was prepared by the sol-gel reaction of 3-(trimethoxysilyl)propyl methacrylates (MPS) with tetraethoxysilane in ethanol; SiO2@PVim were subsequently prepared by grafting PVim chain (Mn = 9800 g/mol, polydispersity index = 1.22) to MPS-SiO2 via the thiol-ene click chemisty. The obtained SiO2@PVim microspheres show higher catalytic activity toward the hydrolysis of p-nitrophenyl acetate compared with the PVim homopolymers. The as-prepared composites have been characterized by scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis and Fourier transform infrared spectrometry analysis. Copyright (C) 2014 John Wiley & Sons, Ltd.