Synthesis and properties of siloxane-crosslinked polyurethane-urea/silica hybrid films from castor oil

Abstract

A novel hybrid diol (HD) crosslinker has been synthesized with hydrolyzable –Si–OR groups from 3-amino propyl trimethoxy silane and 3-glycidoxy propyl trimethoxy silane. Its chemical structure was confirmed by Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy to introduce it as a crosslinker in the castor oil, a renewable resource, to develop functional organic inorganic hybrid coatings. A series of castor oil-based organic–inorganic hybrid materials were prepared from castor oil, isophorone diisocyanate, and the different weight percentages of synthesized HD. Dynamic mechanical thermal analysis, thermogravimetric analysis, differential scanning calorimetry, and the universal testing machine were employed to characterize the hybrid films. The measured properties were found to be strongly influenced by the weight ratio of HD to the castor oil-based polyurethanes. The glass transition temperatures (Tg) for the cured hybrid films were found to be 26–72°C. Antibacterial activity, in vitro hydrolytic degradation, and swelling properties of the hybrid films have been studied. The cured hybrid films exhibited excellent antibacterial activity, which was enhanced with addition of the HD. The alkoxy silane-crosslinked castor oil-based coatings have shown better mechanical and viscoelastic properties in comparison to the control (uncrosslinked castor oil-based polyurethane-urea) coatings. The results showed that the weight percent of the HD is the main factor that controls the thermal, antimicrobial, mechanical, swelling, and degradation properties of these hybrid films.