The semi-IPN hydrogels of poly(acrylic acid-acrylamide-butyl methacrylate) and amylose were prepared using 4

4′-bis(methacryloylamino)azobenzene (BMAAB) as a crosslinker.The swelling behavior and degradation of hydrogels air-dried and freezed-dried both were investigated by immersion in buffer solutions of pH=2.2 and 7.4.The results indicate that both types of gels follow the Schott second-order swelling kinetics.Diffusion of water in gels was a non-Fickian process

having a combinational mechanism of diffusion of water molecules and relaxation of the macromolecular chain.However

the diffusion mechanism was dominative for freezed-dried hydrogels.The equilibrium swelling ratio of freezed-dried hydrogels increases remarkablely in pH=7.4 buffer solutions

but almost no change in pH=2.2 buffer solutions.The degradation of gels was carried out in the presence of colon suspension.SEM and degradation of hydrogels show that the degradation ratios of freezed-dried and air-dried gels were 35.3% and 28.1% within 5 days

respectively.It indicates that the degradation can be enhanced in the colon for gels treated by the freezed-dried method.