Fifteen different poly[ (amino acid ester)phosphazenes] were synthesized to study their crystalline character and hydrolysis behavior in the solution and solid states. The polyphosphazenes synthesized were poly [ bis(methy1 glycinat-N-y1)phosphazenel , poly[ bis(ethy1 glycinat-N-y1)phosphazenel , poly [bis(tertbutyl glycinat-N-yl)phosphazene], poly[bis(benzyl glycinat-N-yl)phosphazene], poly[bis(methyl alaninat-N-yl)phosphazene], poly[bis(ethyl alaninat-N-yl)phosphazene], poly[bis(tert-butyl alaninat-N-y1)phosphazene] , poly[ bis( benzyl alaninat-N-yl) phosphazene] , poly [bis(methyl valinat-N-yl)phosphazene] , poly-[bis(ethyl valinat-N-y1)phosphazenel , poly [bis(tert-butyl valinat-N-y1)phosphazenel , poly[bis(benzyl valinat-N-y1)phosphazenel , poly[bis(methyl phenylalaninat-N-y1)phosphazenel , poly[bis(ethyl pheny1alaninat-Ny1)phosphazenel , and poly [bis(tert-butyl phenylalaninat-N-y1)phosphazenel . The fully-substituted polymerswere obtained by treatment of poly(dich1orophosphazene) 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 were performed to estimate the rates of decomposition of the polymers and the duration over which the polymers maintained their structural integrity. The polymers are potential biomedical materials.

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Sugar residues have been linked to cyclic and high-polymeric phosphazenes. Selective blocking of the 1,2-and 5,6-hydroxyl groups of -D-glucose by acetone allowed linkage to the phosphazene via the remaining hydroxyl unit. Hydrolysis of the blocked, sugar-substituted phosphazenes brought about deprotection. The deprotected derivatives were then modified chemically by oxidation, reduction, and acetylation. The resultant high polymers are the first members of a new class of hydrophilic or water-soluble macromolecules. Their properties and structural characterization are discussed.

Four different poly(organophosphazenea) bearing esters of glycolic or lactic acid as side groups have been synthesized in order to investigate their stability in aqueous media. The polymers are polytbis-(ethyl glycolato)phosphazene], poly [bis(ethyl lactato)phosphazene], poly [bis(benzyl glycolato)phosphazene], and poly [bis (benzyl lactato)phosphazene]. The benzyl esters of glycolic and lactic acid were prepared by the base-catalyzed transesterification of their ethyl esters with benzyl alcohol at 90 °C. Poly(dichlorophosphazene) was treated with a large excess of the appropriate sodium acid ester at 50 °C to yield the fullysubstituted polymer. To avoid unwanted molecular weight decline, these polymers were stored under nitrogen or in vacuum. Hydrolytic decomposition profiles in aqueous media were monitored by 31P NMR spectroscopy and by gel permeation chromatography (GPC). The possible utility of these polymers as biomedical materials is discussed.

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