Uchiyama Mineto, Satoh Kotaro, Kamigaito Masami
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
ACS Macro Lett. 2016 Oct 18;5(10):1157-1161. doi: 10.1021/acsmacrolett.6b00541. Epub 2016 Sep 29.
A combination of hydrogen chloride adduct of isobutyl vinyl ether (IBVE-HCl) and various metal salts (AgOTf, AgPF, AgSbF, NaBArF (BArF: [3,5-(CF)Ph]B)) efficiently generated initiating cationic species with different low, weakly, or non-nucleophilic counteranions (OTf, PF, SbF, BArF) and induced a cationic reversible-addition-fragmentation chain-transfer (RAFT) or degenerative chain-transfer (DT) polymerization of IBVE, ethyl vinyl ether, -methoxystyrene, and α-methylstyrene (αMS) in the presence of appropriate thiocarbonylthio compounds or thioethers as reversible chain-transfer agents. The polymerization behaviors in terms of polymerization rate, polymer molecular weight, terminal structure, and stereochemistry were affected by the counteranions, whereas the molecular weight control was achieved by appropriate RAFT or DT agents for all of these counteranions. With a weakly or noncoordinating BArF anion and a trithiocarbonate, a nearly atactic poly(IBVE) with a narrow molecular weight distribution (/ < 1.1) was obtained. When using nonoxoanions, such as SbF, PF, and BArF, in the presence of thioethers, controlled cationic polymerization of αMS was achieved while frequent irreversible β-proton elimination occurred using TfO. Thus, this method widens the scope of living or controlled cationic polymerizations with various counteranions.
异丁基乙烯基醚的氯化氢加合物（IBVE-HCl）与各种金属盐（AgOTf、AgPF、AgSbF、NaBArF（BArF：[3,5-(CF)Ph]B））的组合，能高效生成带有不同低亲核性、弱亲核性或非亲核性抗衡阴离子（OTf、PF、SbF、BArF）的引发阳离子物种，并在合适的硫代羰基硫化合物或硫醚作为可逆链转移剂存在的情况下，引发异丁基乙烯基醚、乙基乙烯基醚、对甲氧基苯乙烯和α-甲基苯乙烯（αMS）的阳离子可逆加成-断裂链转移（RAFT）或退化链转移（DT）聚合反应。聚合速率、聚合物分子量、末端结构和立体化学方面的聚合行为受抗衡阴离子影响，而对于所有这些抗衡阴离子，通过合适的RAFT或DT试剂实现了分子量控制。使用弱配位或非配位的BArF阴离子和三硫代碳酸酯时，可得到分子量分布窄（/ < 1.1）的近无规立构聚（异丁基乙烯基醚）。当在硫醚存在下使用非氧阴离子（如SbF、PF和BArF）时，实现了αMS的可控阳离子聚合，而使用TfO时频繁发生不可逆的β-质子消除反应。因此，该方法拓宽了使用各种抗衡阴离子进行活性或可控阳离子聚合的范围。
