| In recent years, the strategies to fabricate inorganic/organic composite microspheres have attract great interests of material scientists, principally because such particles can display novel and enhanced properties (e.g. mechanical, chemical, electrical, rheological, magnetic and optical) by independently altering the composition, dimension and structure. In this study, SiO2/polymer nanocomposite spheres with raspberry-like were obtained via sol-gel method. Also monodisperse hollow silica spheres based on the PNIPAM/SiO2 nanocomposite spheres were prepared via a one-step method. The main contents of the work are as follows:1. Hollow silica nanospheres with mesoporous shells were successfully fabricated with a new one-pot strategy by using a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), as soft template. By simply regulating the solution temperature with respect to the lower critical solution temperature (LCST) of PNIPAM, PNIPAM chains can reversibly form aggregates in aqueous solution. Through adding TEOS and modifying the pH value, the microspheres with PNIPAM as core and the silica as shell are obtained. Then, the temperature of aqueous solution is decreased to dissolve the PNIPAM. Finally, the hollow silica microspheres with the diameter of 150 nm are fabricated.2. Monodisperse raspberry-like silica/polystyrene composite nanoparticles were readily prepared by a single-step sol-gel method. First, we introduce–COOH on the surface of micropheres via the copolymerization of St and AA. Silica nanoparticles from TEOS are adhered onto the modified surface of micropheres. Finally, we centrifugate the solution and dry the sample to obtain SiO2/ PS composite microspheres with raspberry-like structure. The fabricated composite particles have a well-defined structure. The diameter of silica nanoparticles and their coverage degree on the surface of PS spheres could be easily tailored by adjusting the tetraethoxysilane concentration. |
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