摘要:为了研究梳形支化聚合物的结构与性能之间的关系，采用大分子引发剂法，通过稳定自由基聚合与原子转移自由基聚合联用，制备不同支化结构的梳形支化聚苯乙烯。在以苯乙烯和乙烯基苄基氯为共聚单体、BPO/ HTEMPO为引发体系、苯甲醚作溶剂的稳定自由基共聚合反应过程中，苯乙烯和乙烯基苄基氯的转化基本同步，表明乙烯基苄基氯结构单元在共聚物分子链上的分布比较均匀；共聚物的分子量随单体转化率增加而线性增长，分子量分布很窄，表明聚合反应具有“活性”可控的特征。通过改变苯乙烯与乙烯基苄基氯的配比，合成了6个带有不同含量苄基氯侧基的共聚物P（St-co-CMS）。在以P（St-co-CMS）为大分子引发剂的苯乙烯原子转移自由基聚合反应。聚合过程中，在一定单体转化率下，聚合物分子量随单体转化率增加而线性增长，分子量分布较窄，聚合产物具有梳形支化结构。通过选择不同苄基氯侧基含量的P（St-co-CMS）为大分子引发剂，并且控制单体转化率，制备了一系列梳形支化PS，所得支化聚合物的支链长度和支化密度与设计值相符。在P（St-co-CMS）引发的苯乙烯ATRP体系中，由于苯乙烯大分子自由基之间的双基偶合终止，导致聚合反应进行到一定转化率时会发生交联，形成凝胶。P（St-co-CMS）大分子引发剂分子链上的氯甲基含量越多，凝胶点出现的越早。
关键词：梳形支化聚苯乙烯，稳定自由基聚合，原子转移自由基聚合，大分子引发剂
Abstract：In order to research the relationship between the structure and performance of comb-like branched polymers, comb-like branched polystyrene was synthesized by the combination of Nitroxide Mediated Polymerization and Atom Transfer Radical Polymerization with macromolecular as initiator. The Nitroxide Mediated Polymerization was carried out by styrene (St) and chloromethyl styrene (CMS) as monomers, BPO/HTEMPO as initiating system and methyl-phenoxide as solvent. During the reaction, the conversion of the two monomers was nearly the same, showing well distribution of chloromethyl styrene unit in copolymer chain. The molecular weight of copolymer was increased with the conversion of monomer and the molecular weight distribution was narrow, showing the “active” character of the polymerization. By controlling the different mol feed of the two monomers, six different copolymers P (St-co-CMS) with different percentage of benzyl chloride as side group were prepared. Then, Atom Transfer Radical Polymerization was carried out with styrene as monomer and P (St-co-CMS) as macroinitiator. In the process of polymerization, the molecular weight was in linear growth with monomer conversion rate under certain monomer conversion, the molecular weight distribution was narrow, and the final polymers had comb-shaped branched structure. A series of comb-like branched polystyrene were synthesized with different P (St-co-CMS) as macroinitiators by controlling the monomer conversion, and the length of chain and the density of branch were well matched with the designed polymers. The polymerization formed a gel at certain conversion, resulting from combination of the styrene radical in ATRP system. With the increasing of the content of benzyl chloride, the gel point appeared sooner.
Key words: comb-branched polystyrene; Notroxide Mediated Polymerization; Atom transfer radical polymerization; macroinitiator
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