RING-OPENING POLYMERIZATION OF 1,4,8-TRIOXASPIRO[4.6]-9-UNDECANONE - A NEW ROUTE TO ALIPHATIC POLYESTERS BEARING FUNCTIONAL PENDENT GROUPS

A straightforward and very efficient pathway has been reported for the synthesis of a functional derivative of epsilon-caprolactone, i.e. 5- ethylene ketal epsilon-caprolactone. This new monomer has been homopol ymerized and copolymerized with epsilon-caprolactone in a well-control led manner, strongly suggesting absence of any side reactions. Deaceta lization of the polyester chains is complete and reduction of the keto ne groups into hydroxyl groups as well. No chain scission is observed to occur in the course of these two derivatization reactions. Thus, al iphatic polyesters bearing either ketone pendent groups or hydroxyl pe ndent groups can be easily prepared, which raises new application pros pects. These materials proved to be easily redispersed in an aqueous m edium. They form stable colloidal nanodispersions (e.g. 100 nm). These suspensions are stable more than 48 h at room temperature and may be viewed as potential drug colloidal vectors with a core-shell like stru cture. Different types of reactive groups on the surface of these nano particulate vectors are indeed available to the binding of species sel ected for molecular recognition and drug targeting. For instance, the well-known reactivity of ketones toward primary amines is a direct rou te to attach peptides onto biodegradable and biocompatible aliphatic p olyesters. Poly(epsilon-caprolactone) with hydroxyl groups reactive to ward triethylaluminum provides a macroinitiator for lactone and lactid e polymerization, so that biodegradable and biocompatible functional c omb, graft, and dendritic aliphatic polyesters can now be synthesized.