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

•We succeeded in preparing organic/inorganic hybrid photochromic pigments.•The photochromic block copolymers are grafted on silica nanoparticle.•The block copolymers were prepared by a living radical polymerization.•The organic/inorganic hybrid pigments are well-dispersed in tetrahydrofuran and water.•The organic/inorganic hybrid pigments show photochromism in solution and powder.

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 photoisomerization 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.

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