Four new phosphazene polymers were synthesized using an esterification methodology. It was found that poly[bis(4-carboxylatophenoxy)phosphazene] reacts with neat alcohols and catalytic acid at reflux to form polymers with varying chemical and physical properties. Esters were prepared from the following alcohols; 2-methoxyethanol, 2,2’-methoxyethoxyethanol, 2-ethoxyethanol, and 1-butanol. The resulting new polymers were characterized using nuclear magnetic resonance (NMR) spectroscopy and were found to have the expected ester pendant groups homogeneously substituted onto the phosphorus-nitrogen backbone. Laser light scattering (LLS) was used to determine that during the modification process molecular weight of the polymer is conserved, suggesting that under the conditions of the esterification process no chain scission occurs.