载银阴离子PS微球制备及催化性能

Synthesis of polystyrene microsphere immobilized with silver nanoparticles and its catalytic performance

以对苯乙烯磺酸钠为稳定剂,采用阴离子稳定分散聚合法一步制备了单分散聚苯乙烯(PS)微球。并以该微球为模板通过化学沉积和化学镀2种方法制备Ag/PS复合微球,研究了不同制备方法和银氨溶液浓度对复合微球形貌的影响。通过傅里叶红外光谱、X-射线衍射、扫描电镜、热重分析和紫外-可见光谱对微球的组成、结构、形貌、热稳定性及催化性能等进行了表征。结果表明:相比化学沉积法,化学镀法可以明显减少银粒子异相成核,提高微球表面包覆率;复合微球表面形貌可以通过银氨溶液浓度来调节,随银氨溶液浓度提高,制备的Ag/PS复合微球载银量和热稳定性提高;当银氨溶液浓度为3×10-2mol/L时,得到的Ag/PS复合微球表面结构均一,载银质量分数约为33.1%,对硼氢化钠还原对硝基苯酚反应的催化活性最好。

Monodisperse polystyrene microspheres are prepared through one-pot polymerization stabilized with polymerizable anion-charged monomer,sodium styrene sulfonate. Using PS particles as template,Ag / PS composite microspheres are then obtained by electrostatic deposition and electroless plating approach. The influence of synthesis method and [Ag（ NH_3）_2]＋concentration on the morphology of composite microspheres is discussed. The resultant composite microspheres are characterized by Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscopy,thermogravimetric analysis and UV-visible spectroscopic techniques. The results reveal that,in contrast to electrostatic deposition,electroless plating approach can significantly reduce the heterogeneous nucleation and improve the rate of surface coating. Composite microsphere surface morphology can be adjusted by [Ag（ NH_3）_2]＋concentration.With the increase of [Ag（ NH_3）_2]~＋ concentration,the silver loads and thermal stability of the prepared Ag / PS composite microspheres are both improved. When the concentration of [Ag（ NH_3）_2]~＋is 3 × 10- 2mol / L,the surface structure of Ag / PS composite microspheres is uniform and the silver mass fraction is about 33. 1%. The catalytic activity is the best for the reduction of 4-nitrophenol by Na BH4.