One-Pot Synthesis of Bio-Based Polyurethanes with Photothermal Functionality from Recycled Waste PET and Renewable Feedstocks

The exploitation of biomass resources and waste recycling are pivotal strategies for reducing the dependence on fossil resources to develop polyurethane (PU) composites. Here, a strategy in which poly(dimer acid (DA))-BHET polyol oligomer (PDBO) is synthesized by recycled bis(2-hydroxyethyl) terephthalate (BHET) monomer from waste PET and biomass-derived DA is proposed to fabricate high-performance and multifunctional lignin-cross-linked polyurethane (BLPU) via a one-pot method. Based on the interaction between the obtained PDBO as a bridge and nanointerface reinforced by lignin as a natural cross-linking agent, the BLPU with a sustainable feedstock content of 86% shows favorable mechanical properties of tensile strength (9.01 MPa) and fracture strain (476%). Attributed to inherent characteristics of lignin and the dual cross-linking network of dynamic bonds (carbamate bond and hydrogen bond), the BLPU exhibits an excellent photothermal temperature rise effect and outstanding self-healing performance. Importantly, such BLPU not only represents excellent UV shielding performance and advantageous water resistance but also achieves degradability under alkaline conditions and recyclability through solvents for reprocessing. Therefore, it is firmly believed that this work pioneers the value-added utilization of waste recycling and provides a sustainable pathway for bio-based PU composites.