Hydrolysable polylactide-polyphosphazene block copolymers for biomedical applications: synthesis, characterization, and composites with poly(lactic-co-glycolic acid)

This is the first reported synthesis of completely hydrolysable polyphosphazene block co-polymers with bioerodible polyesters. Specifically, poly[(lactic acid)-co-poly(bis-alanine ethyl ester phosphazene)], poly[(lactic acid)-co-poly(bis-valine ethyl ester phosphazene)], and poly[(lactic acid)-co-poly(bis-phenylalanine ethyl ester phosphazene)] block copolymers have been prepared. These block co-polymers are blend compatibilizers used to form miscible polymer systems between poly(lactic-co-glycolic acid) (PLAGA) (50 : 50) or PLAGA (85 : 15) and poly[(bis-alanine ethyl ester phosphazene)], poly[(bis-valine ethyl ester phosphazene)], or poly[(bis-phenylalanine ethyl ester phosphazene)]. The resultant combined systems were characterized using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) to investigate polymer miscibility. The rates of hydrolysis and pH of the hydrolysis media were also examined.