Polyanhydrides are of particular interests as materials for controlled drug release systems due to their excellent surface erosion properties.A novel series of diacids containing ester groups were prepared from 4 (hydroxyalkoxy) benzoic acid reacted with succinic anhydride

maleic anhydride and succinyl dichloride.The polymers were synthesized by melt polycondensation.Monomers and their polymers were characterized by IR

1H-NMR and elemental analyses.The effects of the catalyst on the structure and molecular weights of the polymers were investigated.