Studies on the Growing Species in Living Cationic Polymerization and Synthesis of Various Types of Living Polymers

成功的活性阳离子聚合的一个关键是为特定的生长目标明智地选择反离子。也就是说，适当的亲核反离子稳定生长末端，以导致活性阳离子聚合。为了推广活性阳离子聚合的原理，我们研究了在极性溶剂中活性阳离子聚合的可行性，其中可能涉及解离的自由离子物种。异丁基乙烯基醚的活性聚合。在-78ﾟ℃下，HCl-IBVE加合物(1)/ZnCl2体系在CH2Cl2和ETNO2/CH2Cl2混合物中引发活性聚合，而与EtAlCl2类似的体系则引发常规阳离子聚合。在这些极性介质中，两个体系得到的聚合物具有非常相似的低等规度(介观分数约为56%)，表明传播反应是由自由离子介导的。因此，无论溶剂的极性或自由离子或离子对的参与程度如何，活性阳离子聚合都需要…更多的是一种适当的亲核反阴离子。为了论证自由离子和其他阳离子可聚合单体进行活性聚合的可行性，在-15ﾟC的极性溶剂中，考察了在苯乙烯类化合物中具有较高活性的tBOS的阳离子聚合反应。虽然tBOS是在相对较高的温度下聚合的，但与IBE观察到的那样，在自由离子物种存在的情况下也发生了活性聚合。综上所述，在强极性介质中可以实现活性阳离子聚合，其中解离的自由离子物种参与了扩散反应。这是第一个活性阳离子聚合的例子，它的传播反应是由自由离子介导的。此外，既然本研究已经开发出了新的反应条件，那么从各种不能在以前报道的反应条件下进行活性聚合的单体中可以得到新型的活性聚合物。较少

A key to successful living cationic polymerization is the judicious choice of a counterion for a particular growing end. Namely, a suitably nucleophilic counterion stabilize the growing end to lead to living cationic polymerization. To generalize the principle for living cationic polymerization, we examined the feasibility of living cationic polymerization in polar solvents where the dissociated free ionic species may be involved.Living Polymerization of Isobutyl Vinyl Ether(IBVE). At-78ﾟC,living polymerization was induced with the HCI-IBVE adduct(1)/ZnCl_2 system in CH_2Cl_2 and a EtNo_2/CH_2Cl_2 mixture, whereas similar systems with EtAlCl_2 led to conventional cationic polymerization. In these polar media, both systems gave polymers with very similar and low isotacticity (meso<approximately equal>56%), indicating that the propagating reaction is mediated by free ions. Thus, regardless of solvent polarity, or involvement of free ions or ion pairs, living cationic polymerization requi … More res a suitably nucleophilic counteranion.Living polymerization of p-t-Butoxystirene (tBOS). To demonstrate the feasibility of living polymerization by free ions other cationically polymerizable monomers, cationic polymerization of tBOS,which has higher reactivity among stirene derivatives, was examined with the 1/ZnCl_2 initiating system at-15ﾟC in polar solvents. Although tBOS was polymerized at a relatively higher temperature, living polymerization also occurred in the presence of the free ionic species as observed with IBVE.In summary, living cationic polymerization can be achieved in a strongly polar medium, where the dissociated free ionic species is involved in the propagating reaction. This is the first example of living cationic polymerization whose propagating reaction is mediated by free ions. In addition, now that the novel reaction conditions have been developed in this study, new types of living polymers would be obtained from a variety of monomers whose living polymerization have not been operable under the reaction conditions reported before. Less