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Low-temperature and purification-free stereocontrolled ring-opening polymerisation of lactide in supercritical carbon dioxide
Green Chemistry ( IF 9.3 ) Pub Date : 2020-03-11 , DOI: 10.1039/d0gc00352b
Simon P. Bassett 1, 2, 3 , Andrew D. Russell 3, 4, 5, 6 , Paul McKeown 3, 4, 5, 6 , Isabel Robinson 1, 2, 3 , Thomas R. Forder 3, 4, 5, 6 , Vincenzo Taresco 1, 2, 3 , Matthew G. Davidson 3, 4, 5, 6 , Steven M. Howdle 1, 2, 3
Affiliation  

A stereoselective, solvent-free ring-opening polymerisation (ROP) of lactide (LA) in supercritical carbon dioxide (scCO2) is reported for the first time. The key aim is to exploit scCO2 to lower the temperature of traditional melt polymerisations, lowering the energy requirement and leading to cleaner polymeric materials. We have utilised a zirconium amine-trisphenolate initiator-stereoselective catalyst [(iPrO)Zr(OPh(tBu)2-CH2)3N] to yield highly heterotactic poly(lactide) (PLA) homopolymer (Pr = 0.74–0.84) from rac-LA, demonstrating control of the PLA microstructure in scCO2. In addition, high monomer conversion (86–93%) was achieved in short reaction time (1 h), affording poly(lactide) with a very low degree of transesterification and narrow molecular weight distribution. Most importantly, all the reactions were performed at only 80 °C, almost 100 °C lower than the conventional melt process (typically performed at 130–180 °C), representing a very significant potential energy saving.

中文翻译:

丙交酯在超临界二氧化碳中的低温和无纯化立体控制的开环聚合

首次报道了丙交酯(LA)在超临界二氧化碳(scCO 2)中的立体选择性,无溶剂的开环聚合(ROP)。关键目标是利用scCO 2来降低传统熔融聚合的温度,降低能量需求并生产出更清洁的聚合物材料。我们利用锆胺-三酚盐引发剂-立体选择性催化剂[(i PrO)Zr(OPh(t Bu)2 -CH 23 N]生成高度杂规的聚(丙交酯)(PLA)均聚物(P r = 0.74– 0.84)来自rac -LA,证明了对scCO 2中PLA微观结构的控制。此外,在短的反应时间(1小时)内实现了较高的单体转化率(86-93%),从而提供了具有非常低的酯交换度和窄分子量分布的聚(丙交酯)。最重要的是,所有反应都仅在80°C下进行,比传统的熔融工艺(通常在130–180°C下进行的反应)低了近100°C,这代表了非常显着的节能潜力。
更新日期:2020-04-24
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