Binary Polymer Brushes on Silica@Polymer Hybrid Nanospheres and Hollow Polymer Nanospheres by Combined Alkyne−Azide and Thiol−Ene Surface Click Reactions

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) (SiO 2 @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 SiO 2 @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-N 3, M n = 2550 g/mol) and thiol-terminated hydrophilic poly(ethylene glycol) (PEG-SH, M n = 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.