writer：Min Ji, Junyou Wang, Xinlin Yang*
keywords：Hollow polymer microsphere; Movable core; Polyelectrolyte
source：期刊
specific source：Polymer, 50 (25), 5970-5979 (2009). DOI: 10.1016/j.polymer.2009.10.063
Issue time：2009年
Hollow polymer microspheres with movable quaternary pyridinium polyelectrolyte (PE) cores and various functional groups on the shell-layers, such as hydroxyl, amide, and carboxyl, were prepared by the selectively etching of mid-silica layer with hydrofluoric acid from the corresponding poly(ethyleneglycol dimethacrylate-co-methacrylic acid)@poly(ethyleneglycol dimethacrylate- co-4-vinylpyridinium benzylchloride)/silica/polymer (P(EGDMA-co-MAA) @P(EGDMA-co-VPyBzCl)/SiO2/polymer) tetra-layer microspheres. The tetra-layer hybrid microspheres were synthesized by a multistage reaction process, which included the combination of distillation precipitation polymerization for the formation of polymer-layers and the hydrolysis of tetraethyl orthosilicate (TEOS) via a modified
Sto¨ber sol–gel procedure to afford silica layer. The efficient electrostatic interaction between the cationic pyridinium species on the surface of P(EGDMA-co-MAA)@P(EGDMA-co-VPyBzCl) cores and the negative charges on the silica species was essential to get monodisperse tri-layer P(EGDMA-co-MAA)@P(EGDMAco-VPyBzCl)/SiO2 microspheres during the hydrolysis of TEOS. The functional polymer shell was encapsulated over 3-(methacryloxy)propyl trimethacrylate (MPS) modified tri-layer polymer/silica seeds
by distillation precipitation copolymerizations of N,N0-methylenebisacrylamide (MBAAm) crosslinker and comonomers with different functional groups, including polyisopropylacrylamide (NIPAAm), 2-hydroxyethylmethacrylate (HEMA) and methacrylic acid (MAA), with 2,20-azobisisobutyronitrile (AIBN) as an initiator in neat acetonitrile. The morphology and structure of the tetra-layer hybrid microspheres and the corresponding hollow microspheres with movable PE core and functional polymer shell-layer were characterized by transmission electron microscopy (TEM), Fourier-transform infrared
spectroscopy (FT-IR), x-potential, and dynamic light scattering (DLS).