Synthesis and characterization of a polyphosphazene with propyl oxybenzoate,methoxyethoxyethoxy and ethyl glycinate side groups

A biodegradable thermoresponsive polyphosphazene with propyl oxybenzoate,ethyl glycinate and methoxyethoxyethoxy side groups was synthesized via the macromolecular substitution reactions.Its structure was confirmed by 31P NMR,1H NMR,IR,elemental analysis and DSC.Its molecular weight was determined by GPC.The thermoresponsive properties and hydrolytic degradation of the polymer were studied as a function of pH.The LCST of the polymer was found to be almost independent on the pH change and its concentration at higher concentration.Due to the introduction of hydrophobic propyl oxybenzoate and ethyl glycinate side groups into the polymer,the LCST of the polymer was near body temperature and was lower than that of polybis(methoxyethoxyethoxy)phosphazene.The hydrolytic degradation of the polyphosphazene was pH-sensitive.The polymer was hydrolyzed faster in both acidic and basic buffer solution than in neutral buffer solution.On base of its thermoresponsiveness and biodegradability,the polyphosphazene may be promising for biomedical applications.