Coordinative Ring-Opening Copolymerization of Limonene Carbamate and ε-Caprolactone Toward Phosgene- and...

Polyesterurethanes are versatile polymers widely utilized in applications such as foams and adhesives, yet their industrial production relies on toxic and carcinogenic diisocyanates. To address this, isocyanate- and phosgene-free synthetic methods have been explored, with ring-opening polymerization of cyclic carbamates emerging as a promising alternative. This study presents the coordinative ring-opening copolymerization of limonene-based cyclic carbamates with ε-caprolactone to synthesize AB-block polyesterurethanes. Using the presented method, tunable block copolymer compositions were achieved, verified by NMR, GPC, and FT-IR analyses. Thermal and optical characterizations by DSC and UV-vis revealed an adjustable glass transition temperature between -9°C and -59°C and transmittance up to 84% for PLU-b-PCL (49:51), while tensile testing demonstrated customizable mechanical properties. Notably, PLU-b-PCL (5:95) exhibited an elongation at break of 582%. These findings provide a basis for sustainable polyesterurethane synthesis by ring-opening copolymerization and demonstrate the versatility of this method.