Constructing Robust Hard Phases to Achieve a Thermoplastic Polyurethane with Excellent Thermo-Mechanical Properties and Environmental Sustainability

Biobased polymers derived from abundant biomass resources serve as a widely accepted strategy to address the conflicts between fossil energy shortages and the demands of sustainable development. Biomass vanillin diol (VAN–OH), featuring a rigid benzene ring and polar groups (ether and imine bonds), was derived from the modification of vanillin and subsequently copolymerized with polycaprolactone diols and isophorone diisocyanate to synthesize biobased thermoplastic polyurethanes (IVTPUs). FTIR, XRD, and DSC analyses showed that by adjusting the molar ratio of VAN–OH to 1,4-butanediol (BDO), TPU hard segments with different strengths were obtained. The rigid molecular chains of IVTPUs undergo sufficient thermal relaxation to improve the compatibility between the soft and hard chains, which gives IVTPUs excellent thermo-mechanical properties. The IVTPU prepared exclusively by VAN–OH reached the highest tensile strength and toughness of 60.5 ± 5.8 MPa and 229.4 ± 29.6 MJ/m3, respectively. In addition, IVTPU demonstrated better heat resistance (T50% = 393.7 °C). Systematic chemical degradation evaluations have shown that IVTPU films can be degraded by acid solutions more quickly and thoroughly. The mass loss of IVTPU was as high as 84.74% at 1 M HCl and 80 °C. Soil burial experiments verified the occurrence of biodegradation for IVTPU under natural environments. We have successfully prepared biobased TPUs with excellent mechanical properties, degradability, and heat resistance. This is expected to provide additional options for synthesizing biobased TPUs from biomass resources to replace traditional petroleum-based products.