Chemically Recyclable CO2 -Based Solid Polyesters with Facile Property Tunability.

Synthesizing chemically recyclable solid polymeric materials is a significant strategy to potentially achieve carbon neutral production of new polymers and alleviate plastic pollution, especially when the synthesis is based on CO2 and inexpensive co-feedstocks available in large scales. Additionally, polymeric materials should have high enough molecular weight to exhibit distinguished properties from low molar mass polymers to serve for a broader range of application scenarios. However, up to now, strategies for developing solid-state CO2 -based chemically recyclable polyesters with both high molecular weight and facile property tunability are still unprecedented. Herein, a brand-new synthetic route is developed to synthesize chemically recyclable CO2 -based solid polyesters with high molecular weight (Mn up to 587.7 kg mol-1 ) and narrow dispersity (D < 1.2), which should further broaden the potential application scenarios of new CO2 -based polyesters. Additionally, complete monomer recovery from poly(δLH2 ) material is also achieved. The preserved terminal alkene groups allow facile property tuning of the polyesters via photo-initiated thiol-ene click reactions, enabling more potential utilities and further functionalizations.

Chemically recyclable polyesters from CO2, H2, and 1,3-butadiene.

Chemically recyclable solid polymeric materials with commercializable properties only using CO2 and inexpensive bulk chemicals as chemical feedstock can open a brand-new avenue to economically viable, large-scale fixation of CO2 over a long period of time. Despite previous great advancements, development of such a kind of CO2-based polymers remains a long-term unsolved research challenge of great significance. Herein, we reported the first methodology to polymerize six-membered lactone with two substituents vicinal to the ester group (HL), a compound previously found to be non-polymerizable. The present methodology enables the first synthesis of chemically recyclable solid polyesters (polyHL) with a high CO2 content (28 wt %) and large molecular weights (M n up to 613.8 kg mol-1). Transparent membranes with promising pressure-sensitive adhesive (PSA) properties comparable with their commercial counterparts can be conveniently fabricated from the polyesters. Mechanistic studies indicate that rigorous removal of water impurity is the key to the successful polymerization of the relatively inert disubstituted six-membered lactone. A complete monomer recovery from polyHL was also successfully achieved under mild catalytic conditions. The synthesis of polyHL only requires CO2 and two inexpensive bulk chemicals, H2 and 1,3-butadiene, as the starting materials, thus providing a new strategy for potential scalable chemical utilization of CO2 with desirable economic values and concomitant mitigation of CO2 emissions. This work should inspire future research to make useful new solid CO2-based polymers that can meaningfully increase the scale of chemical utilization of CO2 and promote the contribution of chemical utilization of CO2 to global mitigation of CO2 emissions.