不同双硫酯用量下RAFT自由基交联聚合体系的反应动力学及交联结构

考察了二硫代苯甲酸苄酯(BDB)用量对二甲基丙烯酸聚乙二醇酯/甲基丙烯酸聚乙二醇甲基醚酯可逆加成-断裂链转移(RAFT)自由基交联聚合动力学、凝胶行为和交联结构的影响.随BDB用量增加,增长自由基浓度降低,导致聚合速率不断下降.链自由基与休眠链的加成反应进入扩散控制后使得RAFT交联聚合出现自加速,随BDB用量增加自加...

Kinetics of RAFT Radical Crosslinking Polymerization and Crosslinking Structure With Different Dithioester Concentrations

Reaction kinetics,gelation behavior and crosslinking structures of reversible addition-fragmentation chain transfer(RAFT) radical polymerization of poly(ethylene glycol) dimethacrylates(PEGDMA) and poly(ethylene glycol) methyl ether methacrylate(PEGMEMA) with different molar ratios of benzyl dithiobenzoate(BDB) as RAFT agent were investigated.With the increase of BDB molar ratio,concentration of the growing radicals was reduced in the reaction systems,resulting in the decrease of polymerization rate.Due to diffusion-controlled addition of growing radicals to the dormant species,significant autoacceleration occurred in the RAFT polymerization processes.The vinyl conversions at the onset of autoacceleration increased with BDB molar ratio.Gel point reduced as the BDB concentration increased when BDB molar ratio was between 0～1.0,and it increased as more BDB was introduced.The high molar ratio of BDB also gave rise to a high crosslinking density of the final RAFT products,and more homogeneous networks.