Properties of alkoxysilane castor oil synthesized via thiol-ene and its polyurethane/siloxane hybrid coating films

We developed a new silanized castor oil (MSCO) composed of castor oil and 3-mercaptopropyl trimethoxy silane via thiol-ene coupling (TEC). This MSCO was used as a functional polyol in the preparation of a series of bio-based polyurethane/siloxane (SiPU) hybrid coatings through reactions with different castor-oil-and-isophorone-diisocyanate (IPDI) ratios. The SiPU films exhibited better mechanical and thermal properties than castor oil-based coatings without MSCO. The cross-linked structure of the obtained hybrid materials was confirmed by Fourier transform infrared (FTIR) spectroscopy, whereas the morphologies and surface roughness of the hybrid-coating films were observed by scanning electron microscopy (SEM). A slight phase separation was observed in the obtained hybrid materials. The introduction of a silica network can reduce the surface energy of the obtained hybrid materials. The thermal stability of the obtained hybrid materials increases with increasing Si content. The obtained hybrid materials can be applied in coatings as a result of these characteristics, and this study provides an alternative method of preparing hybrid materials from renewable sources.