苯乙烯和N-乙烯基吡咯烷酮共聚物/Ag复合微球的制备及性能研究

首先用无皂乳液聚合法制备了单分散聚苯乙烯(PSt)乳液,以此为种子乳液,使用N,N-亚甲基双丙烯酰胺(MBA)为交联剂,过硫酸钾(KPS)为引发剂,进行苯乙烯和N-乙烯基吡咯烷酮(NVP)共聚合制备了以PSt为核、St和NVP共聚物为壳的具有核-壳结构的聚合物微球(P(St-NVP)).以此微球为模板通过化学沉积法得到了粒径分布均匀、单分散的P(St-NVP)/Ag复合微球.傅里叶红外光谱、X-射线衍射、扫描电镜、透射电镜、激光粒度仪和紫外-可见光谱对复合微球的结构、形貌、物相及催化性能进行了表征.结果表明,P(St-NVP)/Ag复合微球具有规则的球形结构,粒径在400～700 nm之间,随交联剂浓度或种子乳液浓度的增加,复合微球粒径减小.粒径在十几个纳米左右的银粒子均匀分布在微球表面和内部.载银复合微球在NaBH4还原4-硝基苯酚为4-氨基苯酚的模型反应中表现出较高的催化活性.

PREPARATION AND PROPERTIES OF POLY (STYRENE-N-VINYL-2-PYROLIDONE)/Ag COMPOSITE PARTICLES

Polymer particles with core-shell structure,P(St-NVP),based on styrene(St) and N-vinyl-2-pyrrolidone(NVP) were prepared through emulsion polymerization using potassium persulflate(KPS) as the initiator,methylenebisacrylamide(MBA) as the crosslinker in the presence of polystyrene(PSt) seed latex particles synthesized by surfactant-free emulsion polymerization.Using the P(St-NVP) particles as template,P(St-NVP)/Ag composites were obtained by chemical deposition.The morphology,component,structure and catalytic performance of the composite particles were characterized and investigated by Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscopy,transmission electron microscopy,laser diffraction particle size analysis and UV-visible spectroscopic techniques.The results revealed that the P(St-NVP)/Ag composite particles were of spherical particles with quite narrow size distribution.The particle size was between 400 nm and 700 nm,depending on the preparation conditions.The size decreased with the increase in the amount of the crosslinker and the concentration of the seed latex polymer.Ag nanoparticles of about 10 nm in diameter were well coated on the surface of,or implanted inside,the particles due to the complexation of functional groups on polymer chains.The observed diffraction peaks of the composite particles showed that the Ag particles were of face centered cubic crystal structure.The composite particles with Ag nanoparticles were used as the oxidant in 4-nitrophenol reduction to 4-aminophenol with NaBH4 as the reducer,and the reduction was significantly enhanced with the presence of Ag nanoparticles.