Synthesis and characterization of a novel internal emulsifier derived from sunflower oil for the preparation of waterborne polyurethane and their application in coatings

A renewable, green and scalable dihydroxy acid was synthesized from sunflower oil and applied as a chain extender in the preparation of waterborne polyurethanes. In order to prepare dihydroxy acid, epoxidized sunflower oil was ring-opened with methanol followed by saponification. Chemical structure of dihydroxy acid verified by FT-IR and 1H NMR spectroscopies. Acetone process was used as a main method for the synthesis of waterborne polyurethane nanoparticles from Poly(1,4-butylene adipate) (PBA) and dihydroxy acid. Particle size and morphology of nanoparticles were investigated by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM), respectively and confirmed the narrow distribution with small particle diameters of nanoparticles (50-100 nm). The stable dispersion of nanoparticles applied for the preparation of films and subsequent characterizations of their thermal and mechanical properties. The obtained results corroborated that these kinds of novel waterborne polyurethane nanoparticles would be extensively efficient and applicable in coatings.