Synthesis of biodegradable polymers via thiol-ene click polymerization

Abstract

Biodegradable polymers can be used in variable applications within the field of biomedical sciences such as drug delivery systems, scaffolding, sutures and other. To produce these structures a novel and efficient method is explored to synthesize new materials with superior characteristics that may replace existing polymers in the future. In this project polymer networks are synthesized using thiol-ene click step growth polymerization. The used non-radical thiol-ene Michael addition is a fast reaction with high yields, which proceeds at room temperature with small amounts of catalyst, a tertiary phosphine. For the purpose of this thiol-ene step growth polymerization a dithiol homotelechelic polystyrene polymer is synthesized via RAFT polymerization using a bifunctional RAFT-agent (BiDoPAT) and subsequent aminolysis of the RAFT end groups. The resulting polymer is successfully conjugated with acrylic linkers (Mn of 7000 and tailing towards 100000 g'mol-1). By using acrylic linkers biodegradability is introduced via its ester moieties, which are spread throughout the entire molecule. A Baylis-Hillman step growth polymerization is a different method to produce polymers containing ester and accessible vinyl functionalities. The latter can be exploited to crosslink the residual Baylis-Hillman polymers. Furthermore a preliminary study was carried out using a suspension technique to synthesize degradable particles. The characteristics of the above mentioned polymers can be further tuned depending on the product's fate