Synthesis of anti-ultraviolet and fluorescent waterborne polyurethanes with highly active plant oil-based internal emulsifiers

The creation of bio-based internal emulsifiers with highly active primary hydroxyl groups from renewable resources is a key challenge from the perspective of sustainable development. In this study, a combination of transamidation and thiol-ene click reaction was used to synthesize three novel plant oil-based internal emulsifiers with an excellent carbon-carbon double bond conversion exceeding 94 % at room temperature. Combining these internal emulsifiers with commonly used polyols, a series of bio-based waterborne polyurethanes (WPU) with tailored mechanical properties, thermo-physical properties, and thermal stability were prepared through self-ionic emulsion strategy. The results indicated that, due to the unique structures of these plant oil-based internal emulsifiers, the WPU films prepared with them demonstrated better anti-ultraviolet performance (1.18 % transmittance) than those prepared from commercially available internal emulsifiers. Additionally, they also exhibited fluorescence performance under 365 nm excitation, and no fluorescence quenching occurs under stretching state. These bio-based WPU are promising for applications in advanced coatings, sunscreen formulations, and fluorescent pigments.