Synthesis and characterization of amphiphilic silica nanoparticles covered by block copolymers branching photochromic diarylethene moieties on side chain

Silica nanoparticles covered with polystyrene branching diarylethene moieties to the side chains are synthesized by reversible addition-fragmentation chain transfer polymerization on silica nanoparticles. The resulting nanoparticles are soluble in toluene and tetrahydrofuran and show reversible photo-isomerization upon alternating irradiation with ultraviolet and visible light. The photoreversible isomerization follows color change, which is called photochromism. During the photochromic reactions, the nanoparticles are dispersed in solutions such as tetrahydrofuran. The modification by further block copolymerization of N-isopropylacrylamide results in fabrication of photochromic silica nanoparticles soluble in both tetrahydrofuran and water. (C) 2014 Elsevier Ltd. All rights reserved.