title: One-pot preparation of thermoresponsive silica-poly(N-isopropylacrylamide) nanocomposite particles in supercritical carbon dioxide.
abstract: Inorganic/polymer nanocomposite silica-poly(N-isopropylacrylamide) (SiO(2)-PNIPA) was successfully synthesized through a one-pot approach in supercritical carbon dioxide (scCO(2)). All raw materials, N-isopropylacrylamide (NIPA), vinyltriethoxysilane (VTEO), tetraethoxysilane (TEOS), initiator 2,2'-azobisisobutyronitrile (AIBN), crosslinker N,N'-methylenebisacrylamide (MBAM) and hydrolysis agent acetic acid (AA) were introduced into one autoclave and the parallel reactions of free radical polymerization and hydrolysis/condensation occurred simultaneously in the reaction mixture with scCO(2) as solvent. The obtained novel composite particles were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The swelling ratios (SR) and lower critical solution temperatures (LCSTs) of the prepared thermoresponsive microspheres were investigated by swelling tests and ultraviolet-visible (UV) spectrophotometry, respectively. TEM images demonstrated that well-dispersed particles with diameter less than 100 nm were formed. The composite microgels exhibited higher LCSTs than poly(N-isopropylacrylamide) (PNIPA) microgels did. The in vitro release simulation of the particles in situ impregnated with ibuprofen indicated that SiO(2)-PNIPA composites could improve the drug releasing effect of the microgels as controlled drug delivery systems.
authors: School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, People's Republic of China.
authors: Chengwei
authors: C
authors: Wang
authors: Jing
authors: J
authors: Wang
authors: Wei
authors: W
authors: Gao
authors: Jiqing
authors: J
authors: Jiao
authors: Huajie
authors: H
authors: Feng
authors: Xin
authors: X
authors: Liu
authors: Liuping
authors: L
authors: Chen