Synthesis and properties of novel network polymers containing castor oil and silsesquioxane moieties

Abstract

Novel network polymer precursors were synthesized with castor oil or branched poly(l-lactic acid) and 3-(triethoxysilyl)propyl isocyanate. The network polymer precursors were cross-linked at 120 °C for 24 h to obtain network polymer films. The film formed from castor oil was easily broken when peeled off of a polytetrafluoroethylene petri dish, while the film formed from branched poly(l-lactic acid) was obtained as a self-supporting film. Thermal stabilities of the obtained films were measured by thermogravimetric analysis. The temperature at which 10% weight loss (Td10) occurred was 298 °C for the film derived from castor oil, and the Td10 of the film made from branched poly(l-lactic acid) was 200 °C. The film obtained using branched poly(l-lactic acid) exhibited elastomeric properties owing to a relatively low glass transition temperature of 3 °C and the onset of a rubbery plateau region at approximately 20 °C, as measured by dynamic mechanical analysis. Furthermore, we also prepared a film using the precursor material together with tetraethyl orthosilicate. The obtained film exhibited a higher thermal stability (Td10=223 °C) than that of the film using branched poly(l-lactic acid). Finally, the cross-linked films were subjected to degradation by exposure to porcine pancreas lipase. The observation of weight loss after 30 days confirmed the degradability of the films. In this study, we were synthesized novel biomass network polymer containing silsesquioxane as inorganic moiety. First, novel network polymer precursors were synthesized with castor oil or branched poly(l-lactic acid) (PLLA) and 3- (triethoxysilyl) propyl isocyanate. Precursors were carried out to cross-link reaction at 120 °C for 24 h, and obtained network polymer films. Furthermore, we were synthesized cross-linked film, which was increased inorganic moiety using tetraethyl orthosilicate.