微波辐照下无皂阳离子聚(St-MMA)高分子纳米粒子的制备和表征

SYNTHESIS AND CHARACTERIZATION OF EMULSIFIER-FREE CATIONIC POLY(STYRENE-METHYLMETHACRYLATE) NANOPARTICLES UNDER MICROWAVE IRRADIATION

讨论了微波辐照下 ,以丙酮 水为分散介质 ,利用阳离子型自由基引发剂偶氮二异丁基脒盐酸盐(AIBA)引发苯乙烯 (St)和甲基丙烯酸甲酯 (MMA)共聚 ,合成出表面带正电荷的P(St MMA)共聚物纳米粒子 ,考察了丙酮用量、单体和引发剂浓度对纳米粒子粒径、粒径分布和乳液稳定性的影响 .结果表明 ,丙酮 水的体积比由 0增加到 1 2 6∶1时 ,粒子的平均水化半径从 12 2 2 1nm降低到 2 4 6 8nm ,粒径分布变宽 ,乳液抗电解质稳定性逐渐增强 ;增加引发剂和共聚单体MMA的浓度 ,粒子的水化半径逐渐减小 ,粒径分散系数增大 .

Emulsifier-free cationic poly(styrene-methylmethacrylate) (P(St-MMA))copolymer nanoparticles were synthesized under microwave irradiation in the presence of cationic radical initiator 2,2′-azaobisisobutyramidine dihydrochloride(AIBA). Several factors affecting the polymerization were discussed. The polymer conversion was followed gravimetrically at different time intervals during the reaction. The particles were characterized using TEM, LLS.The latex stability in electrolyte-resistance was determined by the critical coagulation concentration of electrolyte.The results indicated that in acetone-water medium, the average particle hydrodynamic radius of P(St-MMA) decreased from 122\^21?nm to 24 68?nm with the addition of acetone/water volume proportion in the range of 0～1\^26∶1, and the stability of latex increased, but the polymerization rate was lowered and the particle distribution broadened. With increasing the concentration of methylmethacrylate or AIBA, the particle size dropped and the polydispersity index enlarged.