Functionalization of waterborne polyurethane with rosin and epoxidized soybean oil for high-performance, UV-shielding, and hydrophobic biobased films and cotton coatings

The development of high-performance waterborne polyurethane (WPU) from biomass materials represents a significant issue in green industry. In this work, a rosin-based epoxidized soybean oil polyol (RE) was synthesized via a ring-opening reaction between rosin acid and epoxidized soybean oil. RE was employed as a functional monomer in combination with castor oil to fabricate films (RECO-WPU), which exhibited excellent balance of mechanical strength, UV shielding and hydrophobicity. Characterization results confirmed the successful covalent incorporation of RE into the polyurethane network with its rigid aromatic structure well preserved, which led to significantly enhanced tensile strength and hydrophobicity. The tensile strength at break increased by 326.1 %, while the water contact Angle rose by 24.5 %. Moreover, RECO-WPU demonstrated remarkable UV-blocking performance, achieving near-complete blocking of UVB and UVC radiation and up to 63.2 % shielding efficiency in UVA region. Furthermore, a durable cotton fabric coating was prepared by impregnating cotton fabric with RECO-WPU emulsion. After five water washes, the water contact Angle of the fabric only decreased by 3.2 % and remained as high as 117.1°, and the UVA transmission rate was only 44.7 %. In addition, the coated fabric also demonstrated washing tolerance to HCl, NaCl and ethanol. This paper proposes a new strategy for developing high-performance, environmentally friendly and structurally stable WPU by utilizing renewable biomass resources. • Preparation of a bio-based waterborne polyurethane from rosin, epoxidized soybean oil, and castor oil. • Rosin imparts excellent UV resistance to waterborne polyurethane, thus enhancing its photo-aging stability. • Enhanced service stability of waterborne polyurethane in humid environments via hydrophobicity imparted by rosin units. • This research paves the way for high-performance, environmentally friendly waterborne polyurethanes.