Synthesis of Sulfur-containing Polymers of Uniform Molecular Weight

本研究旨在发展一种合成分子量均匀的含硫聚合物的新方法，其结果包括：（1）发展了三元环硫醚的新型活性聚合（环硫化物）以得到具有均匀分子量的聚硫醚，和（2）第一个实施例是环硫化物和环氧化物的光诱导共聚，通过使用（N-甲基四苯基卟啉合）丙硫基酸锌来实现。尽管已知环硫化物可与阴离子和配位阴离子引发剂聚合，但由于伴随的副反应如单体的容易脱硫，没有报道证明聚合的活性性质的实例。因此，结果（1）是环硫化物活性聚合的第一个明确的例子。至于结果（2），环硫化物和环氧化物的共聚通常非常困难，因为前者的可聚合性比后者高得多，并且没有成功的报道。另一方面，当使用（N-甲基四苯基卟啉）丙硫酸锌作为引发剂时，环硫化物和环氧化物在可见光照射下发生共聚，得到相应的共聚物。在适当的条件下，所制备的共聚物具有窄的分子量分布。与此形成鲜明对比的是，形成了具有非常宽的分子量分布的嵌段序列的共聚物和/或均聚物的混合物。因此，这是具有非常不同的可聚合性的共聚单体的光增强可共聚性的第一个例子。

The present research is to develop a novel method for the synthesis of sulfur-containing polymers with uniform molecular weights.The results include the (1) development of novel living polymerization of three-membered cyclic thioethers (episulfides) to give polythioethers with uniform molecular weights, and (2) the first example the photo-induced copolymerization of episulfide and epoxide, achieved by using (N-methyltetraphenylporphinato) zinc propanethiolate. Although episulfides have been known to be polymerizable with anionic and coordinate anionic initiators, no example which demonstrates the living nature of polymerization has been reported due to the concomitant side reactions such as a facile desulfuration of the monomer. Therefore, the result (1)is the first clear example of living polymerization of episulfides. As for the result (2), copolymerization of episulfides and epoxides is usually very difficult due to the much higher polymerizability of the former than the latter, and no success has been reported. On the other hand, when (N-methyltetraphenylporphinato) zinc propanethiolate is used as initiator, the copolymerization of episulfides and epoxides takes place under the irradiation with visible light, affording the corresponding copolymers. Under appropriate conditions, the produced copolymers have narrow molecular weight distributions. In sharp contrast, the copolymer of block sequences and/or the mixture of the homopolymers with very broad molecular weight distribution is formed. Therefore, this is the first example of photoenhanced copolymerizability of comonomers with very different polymerizabilities.