Low-temperature and purification-free stereocontrolled ring-opening polymerisation of lactide in supercritical carbon dioxide

Bassett, Simon P.; Russell, Andrew D.; McKeown, Paul; Robinson, Isabel; Forder, Thomas R.; Taresco, Vincenzo; Davidson, Matthew G.; Howdle, Steven M.

Abstract

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.

Citation

Bassett, S. P., Russell, A. D., McKeown, P., Robinson, I., Forder, T. R., Taresco, V., Davidson, M. G., & Howdle, S. M. (2020). Low-temperature and purification-free stereocontrolled ring-opening polymerisation of lactide in supercritical carbon dioxide. Green Chemistry, 22(7), 2197-2202. https://doi.org/10.1039/d0gc00352b

• Journal Article Type: Article
• Acceptance Date: Mar 11, 2020
• Online Publication Date: Mar 11, 2020
• Publication Date: Apr 7, 2020
• Deposit Date: Mar 24, 2020
• Publicly Available Date: Mar 12, 2021
• Journal: Green Chemistry
• Print ISSN: 1463-9262
• Electronic ISSN: 1463-9270
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 22
• Issue: 7
• Pages: 2197-2202
• DOI: https://doi.org/10.1039/d0gc00352b
• Keywords: Pollution; Environmental Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/4139203
• Publisher URL: https://pubs.rsc.org/en/content/articlelanding/2020/GC/D0GC00352B#!divAbstract
• Additional Information: : This document is Similarity Check deposited; : Supplementary Information; : Vincenzo Taresco (ORCID); : Steven M. Howdle (ORCID); : Steven M. Howdle (ResearcherID); : Single-blind; : Received 28 January 2020; Accepted 11 March 2020; Accepted Manuscript published 11 March 2020; Advance Article published 13 March 2020