Toughening CO₂‐Derived Copolymer Elastomers Through Ionomer Networking

Abstract Utilizing carbon dioxide (CO₂) to make polycarbonates through the ring‐opening copolymerization (ROCOP) of CO₂ and epoxides valorizes and recycles CO₂ and reduces pollution in polymer manufacturing. Recent developments in catalysis provide access to polycarbonates with well‐defined structures and allow for copolymerization with biomass‐derived monomers; however, the resulting material properties are underinvestigated. Here, new types of CO₂‐derived thermoplastic elastomers (TPEs) are described together with a generally applicable method to augment tensile mechanical strength and Young's modulus without requiring material re‐design. These TPEs combine high glass transition temperature (T_g) amorphous blocks comprising CO₂‐derived poly(carbonates) (A‐block), with low T_g poly(ε‐decalactone), from castor oil, (B‐block) in ABA structures. The poly(carbonate) blocks are selectively functionalized with metal‐carboxylates where the metals are Na(I), Mg(II), Ca(II), Zn(II) and Al(III). The colorless polymers, featuring <1 wt% metal, show tunable thermal (T_g), and mechanical (elongation at break, elasticity, creep‐resistance) properties. The best elastomers show >50‐fold higher Young's modulus and 21‐times greater tensile strength, without compromise to elastic recovery, compared with the starting block polymers. They have wide operating temperatures (−20 to 200 °C), high creep‐resistance and yet remain recyclable. In the future, these materials may substitute high‐volume petrochemical elastomers and be utilized in high‐growth fields like medicine, robotics, and electronics.