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

15 Scopus citations

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)
Pages (from-to)4512-4522
Number of pages11
JournalChemical Science
Volume13
Issue number16
DOIs
StatePublished - Mar 17 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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