Tailoring the morphology and properties of waterborne polyurethanes by incorporation of acrylic monomers

A series of waterborne polyurethane-acrylate (WPUA) hybrid emulsions in the presence of organic silicon were synthesized by the reaction of isophorone diisocyanate, polytetramethylene ether glycol, double hydroxyl terminated polydimethylsiloxane, methyl methacrylate, and butyl acrylate as mainly raw materials. Three WPUA dispersions with differently internal structures (core-shell, inverse core-shell and semi-interpenetrating network (semi-IPN)) were designed in this study. The morphological analysis was carried out by transmission electron microscopy (TEM) and showed that the designed structures were obtained by changing synthesis method. The mobility of silicon, which affects the water resistance of the films, is determined by the structure of the WPUA and was evaluated by X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements. The degree of silicon migration and water resistance were the highest for the WPUA with the semi-IPN structure. The WPUA with the core-shell structure had the highest tensile strength and the best thermal stability. The WPUA with the inverse core-shell structure had the worst mechanical property. Scanning electron microscopy (SEM) results showed that the WPUA with semi-IPN structure had the highest degree of phase separation.