Abstract

The effect of the hydrophobicity of block copolymer macro-RAFT agents on the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene was investigated. Three different copolymers, poly(dimethyl aminoethyl acrylate) (PDMAEA), poly(dimethyl aminoethyl acrylate-co-styrene)-b-(butyl acrylate) (P(DMAEA-co-St)-b-PBA) and poly(dimethyl aminoethyl acrylate-co-styrene)-b-(hexafluorobutyl acrylate) (P(DMAEA-co-St)-b-PHFBA), which had different hydrophobicity in their hydrophobic segments, were synthesized and used as the macro-RAFT agents. When P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA were used as macro-RAFT agents, the RAFT surfactant-free cationic emulsion polymerization of styrene underwent very fast. But when the PDMAEA was used as the macro-RAFT agent, no polymerization of styrene was observed. The controllability of styrene polymerization with P(DMAEA-co-St)-b-PHFBA as the RAFT agent showed much better than that with P(DMAEA-co-St)-b-PBA as the macro RAFT agent. This was ascribed to hydrophobicity difference of the hydrophobic segment between P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA macro-RAFT agents. A mechanism explanation for the controllability of emulsion polymerization was proposed. The location of the active trithiocarbonate group of the macro-RAFT agent in micelle was supposed to be a key factor affecting the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene. The hydrophobicity of the RAFT agent and nature of medium had impact on the location of the active trithiocarbonate group of the macro-RAFT agent in micelle and affected the polymerization controllability.

摘要

研究了嵌段共聚物大分子RAFT剂的疏水性对苯乙烯无RAFT表面活性剂阳离子乳液聚合反应可控性的影响。三种不同的共聚物，聚（丙烯酸二甲氨基乙基酯）（PDMAEA），聚（丙烯酸二甲氨基乙基酯-共聚物-苯乙烯）-b-（丙烯酸丁酯）（P（DMAEA-共聚物-St）-b -PBA）和聚（二甲基氨基乙基）丙烯酸酯-共-苯乙烯） - b - （六氟丙烯酸酯）（P（DMAEA-共-St） - b -PHFBA），其在它们的疏水性链段具有不同的疏水性，合成和用作大分子RAFT试剂。当P（DMAEA- co -St）-b-PHFBA和P（DMAEA- co -St）-b -PBA作为大分子RAFT试剂，苯乙烯的无RAFT无表面活性剂阳离子乳液聚合反应进行得非常快。但是当将PDMAEA用作大分子RAFT剂时，没有观察到苯乙烯的聚合。用P（DMAEA-共-St）-b- PHFBA作为RAFT剂的苯乙烯聚合的可控性显示出比用P（DMAEA-共-St）-b- PBA作为大分子RAFT剂的苯乙烯的可控性好得多。这归因于P（DMAEA- co- St）-b- PHFBA和P（DMAEA- co- St）-b之间的疏水链段的疏水性差异。-PBA宏RAFT代理。提出了乳液聚合可控性的机理解释。宏观RAFT剂在胶束中的活性三硫代碳酸酯基团的位置被认为是影响可控制RAFT的无苯乙烯阳离子乳液聚合的可控性的关键因素。RAFT试剂的疏水性和介质的性质影响了胶束中大分子RAFT试剂的活性三硫代碳酸酯基团的位置，并影响了聚合反应的可控制性。