Park In, Ko So Hee, An You Sun, Choi Kyung Ho, Chun Hyunaee, Lee Sangkug, Kim Gyungsoo
Green Chemistry and Manufacturing System Division, Korea Institute of Industrial Technology (KITECH), 35-3, Hongcheonri, Ipjangmyeon, Seobukgu, Cheonansi, 330-825 Chungnam, Republic of Korea.
J Nanosci Nanotechnol. 2009 Dec;9(12):7224-8. doi: 10.1166/jnn.2009.1636.
Monodisperse polystyrene (PS) bead particles (diameter approximately 750 nm) have been synthesized with an initiator, 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA), using a surfactant-free emulsion polymerization. The PS particles charged positively by the cationic initiator exhibit uniform size with a narrow size distribution. The Stöber method was adopted to coat silica on the surface of the PS particles. The silica coatings were performed on different conditions; pH (10.0-12.5), tetraethylorthosilicate (TEOS) concentration (10-40 mM), and reaction time (1-5 h). The reaction rates are too low at low pH (10.0) so that no or little silica is coated on the PS bead particles. At high pH condition (approximately 12.5) relatively rough silica shell and heterogeneous nucleation of silica colloids were observed due to high reaction rate of TEOS hydrolysis and condensation reaction. Smooth surface with uniform thickness of silica shells were obtained at a pH value around 11. Also, the thickness of silica coated on the PS spheres increases with increase of TEOS concentration and reaction time. Silica hollow spheres were also obtained by calcination of the PS-silica core-shell particles.
使用引发剂2,2'-偶氮二异丁脒盐酸盐（AIBA），通过无表面活性剂乳液聚合合成了单分散聚苯乙烯（PS）珠粒（直径约750 nm）。由阳离子引发剂带正电荷的PS颗粒尺寸均匀，尺寸分布窄。采用Stöber法在PS颗粒表面包覆二氧化硅。在不同条件下进行二氧化硅包覆；pH值（10.0 - 12.5）、正硅酸乙酯（TEOS）浓度（10 - 40 mM）和反应时间（1 - 5 h）。在低pH值（10.0）下反应速率过低，以至于PS珠粒上没有或只有很少的二氧化硅包覆。在高pH条件下（约12.5），由于TEOS水解和缩合反应的高反应速率，观察到相对粗糙的二氧化硅壳层和二氧化硅胶体的异相成核。在pH值约为11时获得了具有均匀厚度二氧化硅壳层的光滑表面。此外，包覆在PS球上的二氧化硅厚度随着TEOS浓度和反应时间的增加而增加。通过煅烧PS - 二氧化硅核壳颗粒也获得了二氧化硅空心球。
