Bio-derived high-strength waterborne polyurethane using cellulose-nanofiber-stabilized Pickering emulsion

Renewable biomass resources, including castor oil and cellulose, present promising avenues for sustainable polymer synthesis. This study involved the fabrication of a novel waterborne polyurethane utilizing cellulose nanofibers (CNFs) as a Pickering emulsion stabilizer and castor oil as a bio-derived polyol. Two different CNFs assessed the function of CNFs in stabilizing castor-oil-derived waterborne polyurethane emulsions by the ratio, their concentration and the emulsion storage duration. Dynamic light scattering and rheological assessments established that CNFs significantly enhanced emulsion stability by forming a semi-flexible network, which impeded droplet coalescence. Moreover, the incorporation of CNFs improved the mechanical performance of castor-oil-derived waterborne polyurethane films. Specifically, the addition of 1 wt% of the longer CNF resulted in an increase in the tensile strength and Young's modulus to 21.2 MPa and 91.0 MPa, respectively, signifying improvements of 103.0% and 256.6% over the CNF-free control. This investigation underscores the synergistic potential of biomass-derived nanomaterials in the design of high-performance, environmentally friendly polymers. © 2025 Society of Chemical Industry.