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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 PF 5 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 ( T d > 250 °C) and a wide glass transition temperature ( T g ) 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., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We report the rapid, one-pot synthesis of functional polycarbonates derived from renewable alcohols (i.e., glucose tetraacetate, acetyl isosorbide, lauryl alcohol, and ethanol) and a cyclic carbonate bearing an imidazolecarboxylate. This tandem functionalization/ring-opening polymerization strategy can be performed on multigram scale and eliminates the need for rigorous purification and specialized equipment. A wide range of glass transition temperatures ( T g ) was accessible from these renewable pendant groups (>75 °C T g window). We also synthesized several statistical copolycarbonates to show the thermal properties can be tailored with this tandem method. Additionally, we demonstrate a circular polymer economy via chemical recycling to a cyclic carbonate precursor. This work may facilitate development of sustainable polycarbonates with tailored properties that work toward eliminating plastic waste streams.

Isosorbide is a rigid, sugar-derived building block that has shown promise in high-performance materials, albeit with a lack of available controlled polymerization methods. To this end, we provide mechanistic insights into the cationic and quasi-zwitterionic ring-opening polymerization (ROP) of an annulated isosorbide derivative (1,4:2,5:3,6-trianhydro-d-mannitol, 5). Ring-opening selectivity of this tricyclic ether was achieved, and the polymerization is selectively directed toward different macromolecular architectures, allowing for formation of either linear or cyclic polymers. Notably, straightforward recycling of unreacted monomer can be accomplished via sublimation. This work provides the first platform for tailored polymer architectures from isosorbide via ROP.

To determine if tobacco smoke components directly influence coronary vascular reactivity, we evaluated the contractile effects of prostaglandin (PG)F2 alpha and hypertonic KCl in porcine isolated left anterior descending coronary arteries derived from animals chronically treated (18 weeks) with either water soluble tobacco smoke extract, nicotine alkaloid, or saline. Dosing protocols for the extract and for nicotine were designed to achieve blood levels of nicotine approximating those attained by consumption of 2 packs/day of University of Kentucky 2Rl reference cigarettes. Histochemical evaluation of the arteries indicated that both the extract and nicotine caused expected increases in the collagen content of the tunica media. Neither the water soluble extract nor pure nicotine significantly altered coronary vascular sensitivity (as expressed by the ED50) to KCl or PGF2 alpha. Similarly, neither treatment altered the maximum contractile responses (determined as the tension developed normalized to mg wet wt) evoked by KCl and PGF2 alpha. These results indicate that prolonged exposure to water soluble components of tobacco smoke, in doses sufficient to elevate the collagen content of the coronary vascular wall, do not have direct effects on coronary reactivity to selected vasoconstrictor stimuli.