特殊形态聚合物微球原位负载Ag纳米粒子

Polymeric Microspheres with Special Morphology and Loading of Silver Nanoparticles via in-situ Reduction

以苯乙烯单封端的聚N-异丙基丙烯酰胺（StPNIPAAm）大分子单体为反应性分散稳定剂，使之与丙烯腈（AN）和少量苯乙烯（St）在醇／水混合介质中进行三元分散共聚反应，制得了以聚苯乙烯（PS）为核，表面接枝PNIPAAm的聚合物微球（PNIPAAm-g-PAN／PS）。利用扫描电子显微镜（SEM）观察证实：所得聚合物微球的粒径和表面凸起均一，形态结构规整，其粒径和形态可通过改变聚合反应条件加以控制。以典型配方的聚合物微球为媒介，AgNO3为金属源，乙醇为还原剂，在90℃下使Ag纳米粒子原位负载在PNIPAAmgPAN／PS聚合物微球表面。利用透射电子显微镜（TEM），紫外光谱（UV）及傅立叶红外光谱（FT-IR）对表面负载Ag纳米粒子的聚合物微球样品进行了表征，结果表明：Ag纳米粒子在特殊形态聚合物微球表面负载均匀，通过改变银离子的用量可将Ag纳米粒子的大小控制在3～32nm范围内，最小平均粒径约为6nm。

The poly（N-isopropylaerylamide ） （ PNIPAAm ） grafted polyacrylonitrile/polystyrene （PNIPAAm-g- PAN/PS） microspheres were prepared by dispersion copolymerization of acrylonitrile （AN） and styrene （St） in a mixed solvents of ethanol and water in the presence of PNIPAAm macromonomer with a vinyl benzyl end group as reactive or dispersion stabilizer. The morphology and particle size of the microspheres was observed by scanning electron microscopy （SEM）. It was found that the microspheres have unusual morphologic structures. The diameter and morphology of the microspheres can be controlled through varying polymerization conditions. Silver nanoparticles were then located onto surfaces of the PNIPAAm-g PAN/PS microspheres by in-situ reduction of Ag^＋ ion at 90 ℃ in ethanol water mixed solu tion. The stabilized Ag nanoparticles on the surfaces of the microspheres were characterized by transmi ssion electron microscopy （TEM） and UV visible spectroscopy and Fourier transformed infrared （FT-IR） spectroscopy. The results show the composite materials of silver nanoparticles/microspheres are success fully synthesized. The diameter of silver nanoparticles can be controlled in range from 3 nm to 32 nm by changing the dosage of Ag^＋ ion. The minimum mean diameter of silver nanoparticles is about 6 nm.