分散共聚体系中高分子纳米颗粒的合成与反应机理

Studies on the Synthesis of Polymeric Nanoparticles and Mechanism in Dispersion Copolymerization System

用自由基聚合及端基反应法合成了苯乙烯基封端的聚N 异丙基丙烯酰胺和聚乙二醇大分子单体 .核磁共振分析表明 ,基本上每一个大分子单体末端有一个双键 .将大分子单体与苯乙烯进行分散共聚反应 ,一步法制备得到了表面具有接枝链的高分子纳米级颗粒 .研究结果表明 :大分子单体浓度、苯乙烯单体浓度、引发剂浓度、大分子单体末端官能团种类和反应温度等因素对形成微球的直径有明显的影响 ,高分子微球的直径和形态可通过改变上述反应条件加以控制 .通过实验数据计算得出了高分子微球直径与各种反应因素间的定量关系式 ,对不同体系的成核机理进行了比较 ,得到的结果对其它相似共聚反应体系有一定的指导意义 .

Poly(N isopropylacrylamide)(PNIPAAm) and poly(ethylene glycol)(PEG) macromonomers were synthesized by using radical polymerization and/or changing end group type. It was found that their macromonomers have one vinyl end group for per polymer chain based on the analysis of 1H NMR. The macromonomer was selected as reaction stabilizer in copolymerization systems. Polystyrene particles with nano to micron sizes then were prepared by dispersion copolymerization of styrene with PNIPAAm or PEG macromonomer in ethanol/water mixed solvents for 24 h. The particles with narrow size distribution were obtained and studied by scanning electron microscopy (SEM) and laser light scattering (LLS). It was found that the particle sizes could be controlled by changing concentration of macromonomer and other reaction conditions in nano to micron range.