Polythioethers bearing side groups for efficient degradation by E1cB reaction: reaction design for polymerization and main-chain scission
作者:Ryo Kawatani、Keito Hagiwara、Anri Tanaka、Yasuhiro Kohsaka
DOI:10.1039/d3ra03751g
日期:——
β-positions of ester moieties were substituted with a phenyl group. This slight modification in the polymer structure influenced the monomer structures and polymerization mechanisms. The understanding of reaction mechanisms by model reactions was required to obtain high molecular weights of polythioethers. It was clarified that the consequent additions of 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5
我们之前报道过二硫醇和α-(溴甲基)丙烯酸酯串联反应的缩聚反应,由共轭取代(S N2'反应)和共轭加成(迈克尔加成)反应。所得的聚硫醚通过 E1cB 反应发生主链断裂 (MCS),这是共轭加成的逆反应,尽管由于平衡而无法定量。在此,聚硫醚结构的修饰导致不可逆的MCS,其中酯部分的β位被苯基取代。聚合物结构的这种轻微改变影响了单体结构和聚合机制。为了获得高分子量的聚硫醚,需要通过模型反应来理解反应机理。澄清随后添加了 1,4-二氮杂双环[2.2.2]辛烷 (DABCO)、1,8-二氮杂双环[5.4.0]十一碳烯 (DBU) 和 PBu 3可以有效地获得高分子量。所得的聚硫醚通过与 DBU 的 E1cB 反应被不可逆的 MCS 分解。