Living Radical Polymerization using Organic Selenium Compounds

有机硒化合物在有机化学中非常有用。发现有机硒化合物（苯甲基硒或二苯基二硒）在苯乙烯和甲基丙烯酸甲酯的自由基聚合中起光引发剂的作用，苯甲基硒的碳硒键在光照射下发生均裂，生成苯硒基和苯甲基自由基，苯乙烯单体插入这些自由基中，得到更高分子量的聚合物。所得的聚苯乙烯在ω-末端具有苯硒基，也可用作聚合物光引发剂，并可应用于嵌段共聚物的合成。以1，4-二（对叔丁基苯硒甲基）苯为双功能光引发剂，通过过氧化氢消除ω-端的苯硒基，得到碳-碳双键，再将其转化为环氧封端的聚苯乙烯，最后得到大分子单体。在甲基丙烯酸甲酯的存在下，将两端含硒基的遥爪聚苯乙烯作为聚合光引发剂进行光辐照，得到了与阿坝型三嵌段共聚物相对应的光引发剂。合成了一种新型含硒乙烯基单体对苯硒甲基苯乙烯，并与偶氮二异丁腈进行聚合，得到了相应的均聚物。在甲基丙烯酸甲酯存在下，该单体与苯乙烯的共聚物作为聚合物光引发剂进行光辐照，有效地得到了接枝共聚物。另一方面，该单体在紫外光照射下进行均聚反应，得到超支化聚苯乙烯。

Organic selenium compounds are very useful in organic chemistry. We found that the organic selenium compounds (benzyl phenyl senide or diphenyl diselenide) works as a photoiniferter in radical polymerization of styrene and methyl methacrylate.The carbon-selenium bond of benzyl phenyl selenide undergoes homolytic cleavage on photoirradiation to afford phenylseleno and benzyl radicals, and styrene monomer insert to these radicals to afford polymer with higher molecular weight. The resulting polystyrene having phenylseleno group at theω-end works also as a polymeric photoiniferter, and can apply to the synthesis of block copolymer. Further, the phenylseleno group at theω-end is eliminated by hydrogen peroxide to give carbon-carbon double bond and, followed the resulting polystyrene is converted to epoxy terminated polystyrene, and then macromonomer.1, 4-Bis (p-tert-butylphenylselenomethyl) benzene was used as a bifunctional photoiniferter for the polymerization of styrene and methyl methacrylate. Photoirradiation of telechelic polystyrene having phenylseleno groups at both ends as polymeric photoiniferter in the presence of methyl methacrylarte afforded effectively corresponding to the ABA type triblock copolymers.p-Phenylselenomethylstyrene was synthesized as a novel-selenium-containing vinyl monomer and polymerized with azobisisobutyronitrile to afford corresponding homopolymer. Photoirradiation of the copolymer of this monomer and styrene as a polymeric photoiniferter in the presence of methyl methacrylarte effectively afforded a graft copolymer. On the other hand, the homopolymerization of this monomer under UV irradiation gave a hyperbranched polystyrene.