修饰纳米CdS/聚合物的界面相互作用与光学性能

Effects of surface modification on dispersion of nano-CdS in polymers and their optical properties

采用微乳液法结合原位表面修饰合成了纳米尺度的硫化镉粒子,采用溶液共混和静态铺膜方法制备了纳米粒子/聚合物复合体系,以研究纳米粒子与聚合物间的界面作用.结果表明,经修饰的纳米CdS粒子比较均匀地分散于聚合物基体内,纳米粒子与聚合物基体间存在较强的相互作用.根据复合体系的紫外-可见吸收光谱和荧光光谱,分析了表面修饰(表面修饰剂种类、表面修饰剂用量等)对纳米粒子的分散以及复合体系界面特性的影响,证实了表面修饰剂具有促进纳米粒子分散和消除粒子表面缺陷的作用。

A nano-sized CdS particles was incorporated into polymer films by solvent mixing, casting and evaporating methods. The CdS particles of about 6 nm in size were prepared through micro-emulsion and in-situ surface modification with thiol and imidazole, respectively. It is proved that imidazole modification promotes the dispersion of these nanoparticles into PMMA, while thiol modified ones can be uniformly dispersed into PS matrix due to the selective solubility among the surface modifiers, solvents and polymers. The resultant polymer composites were characterized using optical, structural and thermal techniques. FTIR measurements revealed the formation of strong bonding between the particles and the polymer matrices. Besides the surface modifier, the polymers also help to block the surface defects that trap the charge carriers, resulting in enhanced light absorption and emission behavior. On the other hand, in the presence of CdS particles, the thermal decomposition temperatures of PMMA and PS shifted towards higher temperature region, further demonstrating the interaction between the particles and the polymers. The mechanisms accounting for the variation in the composites optical properties with CdS content and the amount of the surface modifiers were explained on the basis of the effects of surface modifier morphologies, dispersion status of the particles, and the complex interaction among the particles, surface modifiers and polymers.