Preparation and characterization of soybean oil-based waterborne polyurethane/acrylate hybrid emulsions for self-matting coatings†
This work aims to explore the feasibility of self-matting coatings based on soybean oil. A novel reactive waterborne polyurethane (RWPU) dispersion containing unsaturated CC double bonds was synthesized from epoxidized soybean oil (ESO). Subsequently, the RWPU dispersion was copolymerized with hard/soft monomers at different weight ratios to prepare polyurethane/acrylate (MPU) hybrid emulsions. The results reveal the gloss levels of MPUs to be as low as 3.3 gloss units at 60°. A scanning electron microscope and three-dimensional surface profilometer were employed to observe the morphology of the MPU-based films, and the relation between the surface roughness and gloss was determined. Further, thermal gravimetric analysis was conducted to determine the thermal stability of the MPU-based films, and the results denoted that these MPU-based films exhibited excellent thermal stability. Tensile tests indicated that the RWPU dispersion, which was copolymerized at a hard monomer weight of 30%, exhibited a good tensile strength of 13.2 MPa and a high elongation percentage of 578%. Furthermore, after one year, the MPU emulsions exhibited a narrow particle size distribution and their zeta potential values were approximately −30.0 mV, revealing the excellent storage stabilities (>one year) of all the MPU emulsions.