Stereoregular functionalized polysaccharides via cationic ring-opening polymerization of biomass-derived levoglucosan

Mayuri Kiran Porwal, Yernaidu Reddi, Derek Saxon, Chris Cramer, Christopher J. Ellison, Theresa M. Reineke

Research output: Contribution to journalArticlepeer-review

Abstract

We report the facile synthesis and characterization of 1,6-α linked functional stereoregular polysaccharides from biomass-derived levoglucosan via cationic ring-opening polymerization (cROP). Levoglucosan is a bicyclic acetal with rich hydroxyl functionality, which can be synthetically modified to install a variety of pendant groups for tailored properties. We have employed biocompatible and recyclable metal triflate catalysts - scandium and bismuth triflate - for green cROP of levoglucosan derivatives, even at very low catalyst loadings of 0.5 mol%. Combined experimental and computational studies provided key kinetic, thermodynamic, and mechanistic insights into the cROP of these derivatives with metal triflates. Computational studies reveal that ring-opening of levoglucosan derivatives is preferred at the 1,6 anhydro linkage and cROP proceeds in a regio- and stereo-specific manner to form 1,6-α glycosidic linkages. DFT calculations also show that biocompatible metal triflates efficiently coordinate with levoglucosan derivatives as compared to the highly toxic PF5 used previously. Post-polymerization modification of levoglucosan-based polysaccharides is readily performed via UV-initiated thiol-ene click reactions. The reported levoglucosan based polymers exhibit good thermal stability (Td > 250 °C) and a wide glass transition temperature (Tg) window (<−150 °C to 32 °C) that is accessible with thioglycerol and lauryl mercaptan pendant groups. This work demonstrates the utility of levoglucosan as a renewably-derived scaffold, enabling facile access to tailored polysaccharides that could be important in many applications ranging from sustainable materials to biologically active polymers.

Original languageEnglish (US)
JournalChemical Science
Volume13
Issue number16
DOIs
StateAccepted/In press - 2022

Bibliographical note

Funding Information:
This work was supported and funded by the NSF Center for Sustainable Polymers at the University of Minnesota; a National Science Foundation supported Center for Chemical Innovation (CHE-1901635). The authors acknowledge John Beumer for preparing the TOC graphic.

Publisher Copyright:
© 2022 The Royal Society of Chemistry

PubMed: MeSH publication types

  • Journal Article

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