Alternating CO₂ and bicycloalkane copolymerization to circular polyesters

Area of Science:

• Polymer Chemistry
• Sustainable Materials Science
• Catalysis

Background:

• CO2 utilization for polymer synthesis is a long-standing goal, but challenges remain, especially for polyester production.
• Direct copolymerization of CO2 with alkenes to form polyesters is thermodynamically unfeasible.
• Existing methods often require reactive comonomers and catalysts to overcome CO2 fixation barriers.

Purpose of the Study:

• To develop a closed-loop platform for producing high-performance, recyclable polyesters from CO2.
• To achieve direct alternating copolymerization of CO2 with bicycloalkanes (BCB and BCP).
• To enable tailorable material properties and efficient end-of-life recycling.

Main Methods:

• Direct alternating copolymerization of CO2 with bicyclic butane (BCB) and bicyclic pentane (BCP) monomers using an organic catalyst.
• Characterization of resulting high-molar-mass polyesters with defined backbones and high CO2 incorporation (up to 50 mol%).
• Investigation of depolymerization pathways for BCB-CO2 and BCP-CO2 polyesters under specific conditions.

Main Results:

• Successfully synthesized high-performance polyesters via direct alternating copolymerization of CO2 with BCB and BCP.
• Achieved maximum 50 mol% CO2 incorporation with architecturally defined backbones, enabling tunable properties.
• Demonstrated selective depolymerization of BCB-CO2 polyesters to BCB monomers (>90% yield) and BCP-CO2 polyesters to bicyclolactones.
• Established sequential depolymerization-repolymerization cycles for circular material lifecycles.

Conclusions:

• A novel CO2-based polyester platform using bicycloalkanes offers a sustainable route to high-performance polymers.
• The developed polyesters exhibit excellent thermal and hydrolytic stability and can be efficiently recycled.
• This approach provides a viable closed-loop system for CO2 utilization in polymer production.