Photopolymerization of Novel Degradable Networks for Orthopedic Applications

Abstract

Multifunctional anhydride monomers (and oligomers) were developed that react to form highly crosslinked polyanhydride networks. Functionalized monomers (and oligomers) of sebacic acid and 1,6-bis( p -carboxyphenoxy)hexane were synthesized and subsequently photopolymerized. The high concentration of double bonds in the system and the multifunctional nature of the monomer (two double bonds per monomer molecule) led to the formation of a highly crosslinked polymer system in a period of seconds, depending on the initiation rate. Because the crosslinks were hydrolyzable anhydride linkages, the material remained biodegradable and the rate of degradation could be controlled by changes in the network composition and the crosslinking density. The high degree of crosslinking facilitated enhancement of mechanical properties (as compared to their linear counterparts) and also promoted a surface controlled degradation mechanism. The ability to photoinitiate the polymerization could lead to a new generation of orthopaedic implants that would provide surgeons with tremendous ease of placement and greater flexibility in design of fracture fixation systems.