Regulation of Microphase Separation in Bio-based Thermoplastic Polyurethanes Driven by Hard Segment Content

Abstract

Regulation of the microphase-separated structure is critical for high-performance thermoplastic polyurethanes (TPUs). To address the limitations of poor heat resistance and reliance on petrochemical resources in traditional TPUs, bio-based TPUs were engineered using rigid 1,4-phenylene diisocyanate and bio-based poly(trimethylene ether) glycol. The results demonstrate that microstructural evolution, hydrogen bonding network formation, and tailoring of macroscopic properties in TPUs can be realized by varying the hard segment content. Increasing the hard segment content enhanced microstructural ordering, boosting the tensile strength from 6.1 MPa to 22.6 MPa while maintaining an elongation at break above 600%. Crucially, the robust crystalline network enhanced thermal stability of the TPUs, resulting in a maximum 5% thermal deformation temperature of 230.2 °C for TPUs. This work elucidates the structure-property relationships governing microphase separation, empowering the rational design of bio-based materials with exceptional toughness and thermal resistance.