Spirocyclic bisphenoxides of Ge, Zr, and Sn as catalysts for ring-expansion polymerizations of <scp>l</scp>
- and meso-lactide
作者:Steffen M. Weidner、Hans R. Kricheldorf
DOI:10.1002/pola.29259
日期:2018.12.15
germanium, zirconium, and tin were prepared from 2,2′‐dihydroxybiphenyl and 2,2′‐dihydroxy‐1,1′‐binaphthyl. Ring‐expansion polymerizations of l‐lactide are mainly studied at 160 or 180 °C. The reactivity of the catalysts increases in the order: Zr < Ge < Sn. Regardless of catalyst, the weight‐average molecular weights (Mw) never exceed 50,000 g mol−1. The resulting poly(l‐lactide)s are optically pure and
锗,锆和锡的螺环酚盐是由2,2'-二羟基联苯和2,2'-二羟基-1,1'-联萘制备的。的扩环聚合升丙交酯被主要研究在160或180℃。催化剂的反应性按以下顺序增加:Zr 120°C时产生相似的结果,但在100或80°C时产生不同的结果。出乎意料的是,在<140°C时获得了钟形的窄分子量分布,类似于酒精引发的聚合反应中的活性聚合反应模式。还发现了一种不寻常的酯交换机制,可产生奇数个周期的窄分布。©2018 Wiley Periodicals,Inc.J.Polym。科学,A部分:Polym。化学 2018,56,2730年至2738年