Synthesis and characterization of new biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups

Two novel biodegradable thermosensitive polyphosphazenes with lactic acid ester and methoxyethoxyethoxy side groups were synthesized via the macromolecular substitution reactions of poly(dichlorophosphazene) with the sodium salt of lactic acid ester and sodium methoxyethoxyethoxide. Their structures were confirmed by 31P NMR, 1H NMR, 13C NMR, IR, DSC, and elemental analysis. The lower critical solution temperature (LCST) behavior in water and in vitro degradation property of the polymers was investigated. The results indicated that two polymers showed LCST phase transition over a range of concentrations from 0.13 to 15 wt% and pH-sensitive degradation properties.