Synergistic stabilization of beeswax Pickering emulsions by oxidized cellulose/TiO2 for hydrophobic and UV-resistant coatings

This study reports the development of a beeswax-based Pickering emulsion stabilized by TEMPO-oxidized cellulose nanofibers (TCNF) and titanium dioxide nanoparticles (TiO 2 ) as co-stabilizers, aimed at fabricating multifunctional coatings with enhanced hydrophobicity and UV-shielding performance. By systematically varying the TCNF: TiO 2 mass ratio (1:0 to 1:4), the structural characteristics of the composite stabilizers, emulsion stability, rheological behavior, and coating functionality were comprehensively evaluated. The results revealed a synergistic stabilization mechanism: TCNF imparted steric hindrance and electrostatic repulsion to suppress droplet coalescence, while TiO 2 reinforced interfacial mechanical integrity and contributed intrinsic UV-blocking capacity. At a TCNF: TiO 2 ratio of 1:3, the emulsion exhibited optimal comprehensive properties, including high emulsification efficiency, long-term storage stability (30 days), strong interfacial film formation, and a water contact angle exceeding 120° after coating application. Furthermore, the incorporation of TiO 2 significantly improved the UV shielding performance of the coating in both UVA and UVB regions, whereas TCNF reinforced the tensile strength of the paper substrate via hydrogen bonding and three-dimensional network formation. Overall, this work establishes a sustainable strategy for the functionalization of cellulose-based materials and highlights the potential of bio-inorganic composite Pickering emulsions in eco-friendly packaging, specialty papers, and green protective coatings.