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以“Cr~(2+)+BPO”体系,在0～40℃下,引发了一系列烯类单体的聚合。该体系引发的活性自由基聚合反应对单体结构有如下的选择性:α-甲基丙烯酸酯类单体在不高于30℃时能进行活性自由基聚合;其它烯类单体,如丙烯酰胺、丙烯腈、苯乙烯以及α-碳原子上不带甲基的丙烯酸酯类单体,均不能进行;而丙烯酸和α-甲基苯乙烯则不能被引发聚合。当温度高于30℃时,α-甲基丙烯酸酯类单体只能进行一般的自由基聚合。根据聚合结果,讨论了该体系引发活性自由基聚合反应的机理。利用“Cr~(2+)+BPO”体系,使MMA与丙烯腈进行嵌段共聚,共聚产物经分离,得到了较纯的嵌段共聚物,并予以表征。采用ESR和可见光谱,探讨了“Cr~(2+)+BPO”体系陈化反应的机理。
With “Cr ~ (2 +) + BPO” system, polymerization of a series of vinyl monomers was initiated at 0 ~ 40 ℃. The living radical polymerization initiated by the system has the following selectivity to the monomer structure:? -methacrylate monomers are capable of living radical polymerization at temperatures not higher than 30C; other ethylenic monomers such as propylene Amides, acrylonitriles, styrenes, and acrylic monomers without methyl groups on the α-carbon atom all failed to proceed; however, acrylic acid and α-methylstyrene were not allowed to initiate polymerization. When the temperature is higher than 30 ℃, α-methacrylate monomer can only be subjected to general radical polymerization. According to the results of the polymerization, the mechanism of the system initiating living radical polymerization was discussed. The copolymer of MMA and acrylonitrile was block copolymerized by using “Cr ~ (2 +) + BPO” system. The relatively pure block copolymer was obtained and characterized. The mechanism of aging reaction of “Cr ~ (2 +) + BPO” system was discussed by ESR and visible spectrum.