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分别以二乙烯基苯(DVB)、双甲基丙烯酸二缩三乙二醇酯(tri-EGDMA)和1,6-双马来酰亚胺基正己烷(BMIH)为支化单体,采用原子转移自由基聚合合成支化聚苯乙烯;以先核后臂法合成的星状支化聚苯乙烯为参照对合成的支化聚合物的支化形态进行研究.采用气相色谱(GC)、核磁共振氢谱(1H-NMR)和三检测凝胶渗透色谱(TD-SEC)测定了苯乙烯的转化率,聚合物分子量及其分布,特性黏数和均方回转半径.实验结果表明3个支化聚合反应体系内悬垂双键是逐步消耗的,不存在明显的成核过程.反应前期,以形成带有悬垂双键的初级链和轻度支化聚合物为主,聚合物分子量随单体转化率逐步上升;反应后期,悬垂双键聚合导致的分子之间的偶合更加明显,使得聚合物分子量快速上升,合成得到的都是无规支化聚合物.
Divinyl benzene (DVB), triethylene glycol dimethacrylate (tri-EGDMA) and 1,6-bismaleimidohexane (BMIH) Atomic transfer radical polymerization was used to synthesize the branched polystyrene.The branching morphology of the branched polymers was studied by using star-branched polystyrene synthesized by the pronucleus posterior arm method.Using gas chromatography (GC) The conversion of styrene, molecular weight and distribution of polymer, intrinsic viscosity and mean square radius of gyration were measured by 1H-NMR and TD-SEC. The experimental results showed that three The dangling double bonds in the branched polymerization system are gradually consumed, and there is no obvious nucleation process.In the early stage of the reaction, the primary chains with dangling double bonds and the lightly branched polymers are dominant, and the molecular weight of the polymer varies with The conversion rate gradually increased. In the late reaction period, the coupling between the molecules caused by the dangling double bond became more pronounced, leading to the rapid increase of the molecular weight of the polymer, and the random branched polymers were synthesized.