Hairy Hollow Microspheres of Fluorescent Shell and Temperature-Responsive Brushes via Combined Distillation-Precipitation Polymerization and Thiol-ene Click Chemistry

Neal ly monodispersed silica core poly(N-vinylca rbazole) shell (SiO2@PVK) microspheres of 226, 235, and 244 rim in aver au diameters were first synthesized by surface-initiated distillation-precipitation polymerization of N-vinylcal bazole, in the presence of divinylbenzene. from the 197 nm silica template microsphei es prepared by the sol-gel reaction of tetraethyl orthosilicate (TEOS) and 3-(trimethoxysilyppi opyl methacrylate (MPS) The SiO2@PVK-PNIPAM core shell hairy microspheres (PNIPAM = poly(N-isopi opylacrylamrde)) were subsequently prepared by grafting the PNIPAM chains (M-n = 11600 g/mol, polydispei shy inclex = I 32), prepared a priori by reversible addition fragmentation chain transfer (RAFT) polymerization, to the SiO2@PVK-PNIPAM microspheres via the throl ene click chemistry The g 'along density of PN1PAM brushes on the SiO2@PVK-PNIPAM microspheres was about 0 1 chains/nm(2) Hairy hollow miclospheres with a fluorescent and cross-linked PVK shell and temperature-responsive PNIPAM brushes finally obtained, after selective removal of the inorganic silica core from the Si02@PVK PNIP.AM microspheles by 14 F etching The SiO2@PVK-PNIPAM hairy hollow mici spheres were characremed by field-emission scanning electron microscopy (FESEM), transmission electron mica oscopy (TEM), fluorescence spectr oscopy, and dynamic laser scattering (DLS)