A novel hydroxyl polyacrylate latex modified by OvPOSS and its application in two-component waterborne polyurethane coatings

Abstract

Octavinyl polyhedral oligomeric sisesquioxane (OvPOSS) was synthesized via hydrolysis and condensation of vinyltriethoxysilane. The structure of OvPOSS was determined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 1H nuclear magnetic resonance and 29Si nuclear magnetic resonance. A novel hydroxyl functional polyacrylate latex (HPA) with core–shell structure modified by OvPOSS (OvPOSS/HPA) was successfully prepared via emulsion copolymerization. Consequently two-component waterborne polyurethane (2K-WPU) coatings were prepared by using the as-prepared latex as hydroxyl components and hydrophilic polyisocyanates as curing agents. The structure and properties of OvPOSS/HPA were marked by FTIR, XRD, differential scanning calorimetry and thermogravimetric analysis. The results of FTIR and XRD show that OvPOSS has been successfully embedded into HPA, and OvPOSS occupies a homogeneous distribution in the HPA matrix. The effect of OvPOSS on the properties of OvPOSS/HPA as well as the application performance of 2K-WPU coatings film were also investigated. The results show that OvPOSS/HPA possesses core–shell structure with the OvPOSS core and enhanced thermal stability. The glass transition temperature (Tg) of OvPOSS/HPA with 2.0% OvPOSS content is 22.3°C, which is 8.4°C higher than that of pure HPA. The performance properties of the 2K-WPU coating films such as pencil hardness were also improved by incorporation of OvPOSS.