pH值和前驱体用量对核壳结构PSt/SiO2复合微球结构形态的影响

首先通过无皂乳液聚合法制得表面含羧基、粒径为360 nm的单分散聚苯乙烯(PSt)种子乳液,并在EtOH/H2O混合介质中用γ-氨丙基三乙氧基硅烷(KH-550)对其进行改性,制得表面含有活性硅乙氧基并带有正电荷的改性PSt乳胶粒,然后再加入原硅酸乙酯(TEOS)进行共水解与共缩聚反应,制备出了核壳结构PSt/SiO2...

INFLUENCES OF pH AND AMOUNT OF PRECURSOR ON THE MORPHOLOGY OF PSt/SiO2 CORE-SHELL COMPOSITE MICROSPHERES

Monodispersed carboxyl-containing PSt seed latex with the diameter of 360 nm was first synthesized via batch emulsifier-free emulsion polymerization,and the positively charged PSt latex particles with surface reactive ethoxylsilyl groups were then prepared in the medium of ethanol and water using γ-aminopropyl triethoxysilane(KH-550) as modifier,then PSt /SiO2 core-shell composite microspheres were obtained by dropwise adding tetraethoxysilane(TEOS) into the above system.Influences of pH and TEOS amount on the morphology of PSt /SiO2 core-shell composite microspheres were investigated using TEM and SEM.Results showed that the PSt /SiO2 core-shell composite microspheres were generated only under alkaline conditions.When the amounts of PSt seed particles and TEOS was 1.5 g and 5.0 g,respectively,and pH was controlled at 8.5,the encapsulation of PSt seed particles with SiO2 was intact,and the uniform SiO2 shell with about 35 nm was obtained,and after that,the percentage of the composite microspheres partially encapsulated by SiO2 increased with the increase of pH value.With the increase of TEOS amount from 2.5 g to 15 g,the thickness of PSt /SiO2 core-shell composite microspheres gradually increased from 17 nm to 68 nm,but their surface gradually became rough.