POLY[(AMINO-ACID-ESTER)PHOSPHAZENES] - SYNTHESIS, CRYSTALLINITY, AND HYDROLYTIC SENSITIVITY IN SOLUTION AND THE SOLID-STATE

Fifteen different poly[(amino acid ester)phosphazenes] were synthesize d to study their crystalline character and hydrolysis behavior in the solution and solid states. The polyphosphazenes synthesized were poly[ bis(methyl glycinat-N-yl)phosphazene], poly[bis(ethyl glycinat-N-yl)ph osphazene], poly[bis(tert-butyl glycinat-N-yl)phosphazene], poly[bis(b enzyl glycinat-N-yl)phosphazene], poly[bis(methyl alaninat-N-yl)phosph azene], poly[bis(ethyl alaninat-N-yl)phosphazene], poly[bis(tert-butyl alaninat-N-yl)phos-phazene], poly[bis(benzyl alaninat-N-yl)phosphazen e], poly[bis(methyl valinat-N-yl)phosphazene], poly-[bis(ethyl valinat -N-yl)phosphazene], poly[bis(tert-butyl valinat-N-yl)phosphazene],poly [bis(benzyl valinat-N-yl)phosphazene], poly[bis(methyl phenylalaninat- N-yl)phosphazene], poly[bis(ethyl phenylalaninat-N-yl)phosphazene], an d poly[bis(tert-butyl phenylalaninat-N-yl)phosphazene]. The fully-subs tituted polymers were obtained by treatment of poly(dichlorophosphazen e) with a large excess of the appropriate amino acid ester. Several of these polymers were crystalline as measured by differential scanning calorimetry and by polarized optical microscopy. Hydrolysis studies we re performed to estimate the rates of decomposition of the polymers an d the duration over which the polymers maintained their structural int egrity. The polymers are potential biomedical materials.