Binary polymer brushes on silica@polymer hybrid nanospheres and hollow polymer nanospheres by combined alkyne-azide and thiol-ene surface click reactions

Abstract

Silica@polymer core-shell hybrid nanospheres and air@polymer hollow nanospheres with surface-grafted binary polymer brushes were synthesized by a combination of sol-gel reaction, distillation-precipitation polymerization, and dual "click" reactions (alkyne-azide and thiol-ene "click" chemistry). Initially, 179 nm silica@poly(methacrylic acid-co-propargyl methacrylate-co-divinylbenzene) (SiO2@P(MAA-co-PMA-co-DVB)) core-shell hybrid nanospheres were prepared by distillation-precipitation copolymerization of MAA, PMA, and DVB in acetonitrile, using the 151 nm silica nanospheres from sol-gel reaction as templates. The propargyl groups from PMA and residual C=C double bonds from DVB on the SiO2@P(MAA-co-PMA-co- DVB) core-shell hybrid nanospheres provided dual clickable functionalities for the respective alkyne-azide and thiol-ene reactions with the azido-terminated hydrophobic polystyrene (PS-N3, Mn = 2550 g/mol) and thiol-terminated hydrophilic poly(ethylene glycol) (PEG-SH, Mn = 5000 g/mol). Finally, hairy hollow nanospheres with a hollow core, cross-linked copolymer shell, and binary polymer brushes on the shell surface were prepared by selective removal of the inorganic silica core from the SiO 2@P(MAA-co-PMA-co-DVB)-click-PS/PEG nanospheres in HF solution. © 2010 American Chemical Society.