Hollow mesoporous silica nanoparticles modified with coumarin-containing copolymer for photo-modulated loading and releasing guest molecule

Hollow mesoporous silica nanoparticles (HMSNs) grafted with a photo-responsive copolymer containing coumarin groups were successfully prepared. With uniform polystyrene nanoparticles and cetyltrimethylammonium bromide correspondingly as the template of core and channel, HMSNs were made from tetraethyloxysilane in alkalic condition. Epoxy groups were introduced onto the outer surface of HMSNs with c-(2,3-epoxypropoxy) propyltrimethoxysilane and converted into azido groups with sodium azide, resulting in azidofunctionalized HMSNs (azido-HMSNs). Meanwhile, singleelectron transfer-living radical copolymerization of methyl methacrylate (MMA) and 7-(2-methacryloyloxy)-4-methylcoumarin (CMA) with propargyl 2-bromoisobutyrate as the initiator produced alkynyl-capped P(MMA-co-CMA) [alkynyl-P(MMA-coCMA)]. Finally, photo-responsive HMSNs grafted with P(MMAco- CMA) [HMSN-g-P(MMA-co-CMA)] was achieved through the click reaction between azido-HMSNs and alkynyl-P(MMA-coCMA). Different techniques such as transmission electron microscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis confirmed the successful preparation of the resultant hybrid nanoparticles and their intermediates. Because of its hollow core, mesoporous shell channels and light responsiveness, the coumarin-modified HMSNs would be an interesting nano-vehicle for guest molecules. Thus, the loading and release of pyrene with HMSN-g-P(MMA-co-CMA) was studied. (C) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3791-3799