By ester coupling reaction with dicyclohexyl carbodiimide/N

N′-dimethyl amino pyridine as the active carboxyl group reagents

a linear azo polymer was constructed.It combines the unique biocompatibility and hydrophilicity of PEO with the biodegradability and low toxicity of 5

5′-azodisalicylic acid (Olsalazine

OLZ) used in the management of ulcerative colitis.The resultant condensation polymers were characterized by FTIR

NMR

GPC and DSC methods.It was found that changing the molecular weight of PEO blocks affected the loading ratio of OLZ and resulted in significant differences in the hydration and degradability of the condensation polymers.The therapeutically active mesalamine (5-aminosalicylic acid

5-ASA) was released from the aqueous PEO-OLZ condensation polymer solution with cecum contents through azo-reduction and hydrolysis.The resultant azo-containing condensation polymer with azo bonds in the main chain can either be used as a polymeric prodrug for 5-ASA or as a colon specific drug delivery carrier for other bioactive substances.