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合成了S-1-十二烷基-S′-(α,α′-二甲基-α″-乙酸)三硫代碳酸酯(TTC),以此为链转移剂,采用光差动热分析仪(DPC)和动态力学分析(DMA)方法研究了室温条件下紫外光引发的聚乙二醇二甲基丙烯酸酯(PEGDMA)的可逆加成-断裂链转移(RAFT)自由基聚合行为.发现RAFT光聚合反应的反应速率小于常规自由基聚合,因为体系由扩散控制,反应中自加速趋势减缓.探讨了双键之间聚乙二醇链段长度对于聚合速率和最终转化率的影响.结果发现,随着中间聚乙二醇链段的增加,聚合速率先变小再变大,最终转化率缓慢变大.RAFT光交联产物的交联密度随中间链段长度的增加而下降,交联均匀性提高.
S-1-dodecyl-S ’- (α, α’-dimethyl- α "-acetic acid) trithiocarbonate (TTC) was synthesized and used as a chain transfer agent. (DFT) and dynamic mechanical analysis (DMA) were used to study the reversible addition-fragmentation chain transfer (RAFT) radical polymerization of polyethylene glycol dimethacrylate (PEGDMA) initiated by ultraviolet light at room temperature. It was found that the reaction rate of RAFT photopolymerization was less than that of conventional free radical polymerization because the system was controlled by diffusion and the self-accelerating tendency of the reaction slowed down.The effect of polyethylene glycol segment length on the polymerization rate and final conversion was discussed. The results showed that with the increase of the middle polyethylene glycol segment, the polymerization rate became smaller and then larger, and the final conversion rate increased slowly.The crosslink density of the crosslinked product of RAFT decreased with the increase of the middle segment length, Improved cross-linking uniformity.