Biodegradable Comb-like Poly (Vinyl Alcohol)-graft-Poly (P-dioxanone) And Their Blends With Poly (P-dioxanone)

As one of aliphatic polyether-ester, poly (p-dioxanone) (PPDO) shows not only excellent biodegradability, biocompatibility and bio-absorbability, but also good flexility, tensile strength and knot strength. The PPDO has already been used in some biomedical materials such as suture, bone repair device and may have potential application in peroral or parenteral drug delivery systems. Like many other aliphatic polyesters, however, the hydrophobicity may weaken the biocompatibility of PPDO with soft tissues and the affinity with the hydrophilic drugs or biomacromolecules. The PPDO exhibited discontinues degradation behavior due to its hydrophobicity and simicrystallinity. These disadvantages therefore limited the application of PPDO in the biomedical materials. In this work, we adopt the graft copolymerization of PPDO with hydrophilic polymer to improve the properties of PPDO. The amphiphilic graft copolymers based on aliphatic polyesters have potential application in controlled drug delivery and release owing to its special comb-like molecular structure and excellent compatibility with biomacromolecules. We chose poly (vinyl alcohol) (PVA) as hydrophilic backbone because the PVA is the only polymer with carbon-to-carbon chain which has been proved to be biodegradable. Moreover, the PVA has very excellent mechanical strength.A few researches about the graft coplymerization of aliphatic polyesters with PVA have been reported. Since the hydroxyl groups in PVA molecules may act as both initiators and chain transfers in the ring-open polymerization of lactones or lactides, and therefore induced obvious intra- or inter-chain transfer reactions and transesterifications, resulting in an uncontrollable molecular structure. In this work,...