接枝型PUA乳液合成及聚合动力学研究

甲基丙烯酸羟丙酯与水性聚氨酯预聚体反应,得到双烯封端的水性聚氨酯乳液。在乳化剂、引发剂存在下,将丙烯酸酯单体与水性聚氨酯乳液充分混合,并引发聚合,制备了接枝型PUA乳液。TEM观察了PUA乳液的形貌,PUA乳液的粒径在60～120 nm之间;FTIR和NMR表征了合成的PUA结构,显示丙烯酸酯的加入改变了PU本身的氢键相互作用;转化率测试表明,甲基丙烯酸羟丙酯与PU预聚体的反应具有二级动力学特征,而乳化剂的用量影响丙烯酸酯单体与双烯封端聚氨酯乳液的反应速率,反应速率与乳化剂用量符合Rp∝SDS]0.28。

Synthesis of PUA hybrid emulsion and studies on the polymerization dynamics

Water-borne polyurethane with molecular chain end double bond was synthesized by hydroxypropyl methacrylate and polyurethane prepolymer.Graft and crosslinking copolymerization of acrylic/polyurethane(PUA) hybrid emulsion was prepared by water-borne polyurethane modified with acrylic resin.The morphology of PUA latex was shown by TEM and the results indicated that the size of PUA was between 60～120 nm.The structure of PUA was characterized by FTIR and NMR.The results of FTIR indicated that the hydrogen bonding interaction in PU was changed with the addition of acrylic.The conversion of the NCO groups for PU showed that the reaction between hydroxypropyl methacrylate and polyurethane prepolymer possessed secondary dynamics characterization.The content of emulsion agent affected the reaction rate for hydroxypropyl methacrylate and polyurethane prepolymer.The relationship between the rate Rp and the content of emulsion agent accorded with the equation Rp∝0.28.