An Excellent Biobased Copolymerization Monomer Module: Synthesis of Biobased Copolymers with Excellent Heat Resistance and Hydrophilic Properties

The use of biomass feedstocks for the manufacture of high-performance polymers can help expand their range of applications and reduce their dependence on finite fossil resources. However, improving the heat resistance and hydrophilicity of bio-based polyesters remains a significant challenge. Herein, we introduce N,N′ - trans -1,4-cyclohexane-bis(pyrrolidone-4-methylcarboxylate) (CBPC), a novel bio-based tricyclic dibasic ester synthesized from renewable dimethyl itaconic acid and trans -1,4-cyclohexane diamine via an aza-Michael addition reaction. As a unique comonomer, CBPC features a rigid tricyclic backbone that significantly enhances chain packing and thermal stability, whereas its pyrrolidone side groups impart tunable polarity and improved hydrophilicity. Using CBPC, diphenyl carbonate, and 1,4-butylene glycol, a series of PBCC copolymers with 10 mol%–30 mol% CBPC was synthesized via ester-exchange and melt polycondensation methods. Incorporation of CBPC raised the melting temperature ( T m ) from 56.8 °C to 225.8 °C and the initial decomposition temperature ( T d5% ) from 258.0 °C to 306.7 °C, positioning PBCC among the most heat-resistant bio-based polyesters reported. Additionally, the pyrrolidone units enabled transformation from hydrophobic to hydrophilic. This study demonstrates that CBPC is an effective and innovative building block for the design of bio-based polymers with enhanced thermal and surface properties, offering a promising strategy for the development of high-performance sustainable materials.