反相乳液聚合法合成聚丙烯酸纳米及微米颗粒

采用反相乳液聚合方法,合成纳米及微米级尺寸的聚丙烯酸吸水性颗粒.将Span-80和Twoon-80组成的协同乳化体系分散于烷烃介质,使聚合体系稳定化.聚合初期,单体存在于乳化液滴和胶束中.在自由基引发下,聚合得到的聚丙烯酸颗粒大小均一,且其尺寸取决于引发剂的类型.若使用水溶性引发剂,如过硫酸铵,得到微米级的颗粒;若使用油溶性的偶氮二异丁腈作引发剂,由于丙烯酸的齐聚物分子链在油性连续相中溶解受限,则得到纳米级颗粒.

Synthesis of poly(acrylic acid) nano- and microparticles using an inverse emulsion polymerization method

Latices of water-swollen poly(acrylic acid) nano-and microparticles were synthesized using an inverse(w/o) emulsion polymerization method. They are stabilized by a co-emulsifier system consisting of Span80 and Tween80 dispersed in aliphatic hydrocarbons.The initial polymerization medium contains emulsion droplets and inverse micelles which solubilize a part of the monomer solution. The polymerization is initiated by free radicals, and particle dispersions with a narrow size distribution are obtained. The particle size is dependent on the type of radical initiator used. With water-soluble initiators, for example ammonium persulfate, microparticles were obtained in the size range of micro-size. When lipophilic radical initiators, such as azo-bis-isobutyronitrile, are used, almost exclusively nanoparticles are generated , due to the limited solubility of oligomeric poly(acrylic acid) chains in the lipophilic continuous phase.