Synthesis and Characterization of Inorganic-Organic Hybrid Materials Derived from Polysilsesquioxanes (POSS)

This article describes two synthetic strategies of biodegradable multi-arm star polymers with a polyhedral oligomeric silsesquioxane (POSS) core. The goal is to develop synthetic strategies towards reinforced biodegradable polymers that can potentially be used in hard tissue engineering. The polymers were characterized including a preliminary evaluation of the cytotoxicity of the POSS-hybrid polymers and the POSS core. A core first strategy employed the ring opening polymerization of epsilon-caprolactone and/or L-lactide using Sn(Oct)(2) as the catalyst and octa hydroxy silsequioxane as the initiating core. The arm first strategy utilized an esterification reaction between octaanhydride functionalized POSS (POSS-SA) molecule and hydroxyl functionalized polyesters. The hybrid polymers were characterized with FTIR, H-1, C-13, Si-29 NMR, GPC and thermal analysis. The POSS-polymer ratio can be tailored to obtain polymers with different handling properties, from a solid to a viscous liquid. Preliminary cell toxicology studies of octakis hydroxy POSS and hybrid polymers were evaluated using Myoblast (C2C12 cells) and human osteoblast cells (MG63). The studies indicated that there is no significant cell toxicity exhibited by these POSS derived materials demonstrating their potential use as biomaterials.