Chemically Recyclable Unnatural (1→6)-Polysaccharides from Cellulose-Derived Levoglucosenone and Dihydrolevoglucosenone

Abstract

Unnatural polysaccharide analogs and their biological activities and material properties have attracted considerable research interest. However, these efforts often encounter challenges, especially those related to synthetic complexity and scalability. Here, we report the chemical synthesis of unnatural (1→6)-polysaccharides using levoglucosenone (LGO) and dihydrolevoglucosenone (Cyrene), which are derived from cellulose. Using a versatile monomer synthesis from LGO and Cyrene and cationic ring-opening polymerization, (1→6)-polysaccharides with various tailored substituent patterns are obtained. Additionally, environmentally benign and easy-to-handle organic Brønsted acid catalysts are investigated. This study demonstrates well-controlled first-order polymerization kinetics for the reactive (1S,5R)-6,8-dioxabicyclo[3,2,1]octane (DBO) monomer. The synthesized (1→6)-polysaccharides exhibit high thermal stability and form amorphous solids under ambient conditions, which could be processed into highly transparent self-standing films. Additionally, these polymers exhibit excellent closed-loop chemical recyclability. This study provides an important approach to explore the chemical spaces of unnatural polysaccharides and contributes to the development of sustainable polymer materials from abundant biomass resources.

Sugar-Derived Cyclic Acetals as Comonomers for Cationic Copolymerization with Vinyl Ethers

“…Sugars can also be transformed into monomers for chain-growth polymerization. For example, d -xylose-derived cyclic monomers having an oxetane ring were reported to yield high-molecular-weight (high-MW) polymers by ring-opening (co)­polymerization. − An isosorbide-derived cyclic ether was also polymerized by the ring-opening mechanism. , In addition, anhydrosugars (Scheme B), which are synthesized by dehydration reactions of sugars, undergo cationic ring-opening polymerization (ROP) via single ring-opening of the bicyclic acetal structures − in a manner similar to cationic ROPs of not-sugar-derived monocyclic and bicyclic acetals. ,, Recent examples of anhydrosugar polymerization include the design of new monomers and the living cationic polymerization of anhydrosugars. − …”