Bio-inspired gradient materials based on the biodegradable polymer blend are expected to be indispensable to the new approaches for biomedical applications. In this study, multi-step casting self-organization on the aluminum surface are used to control the compositional distribution in the blend films of biodegradable chitosan and poly(ethylene oxide). By this way, three kinds of compositional gradient, i.e., pseudobilayer (PG), gradient (G) and semigradient (SG) blend films, along the film thickness were prepared. Their compositional morphologies were evaluated by means of ATR-FTIR and FTIR mapping measurements. In addition, the moisture absorption behavior and the mechanical properties of the gradient film were characterized with referring their gradient morphologies. It is found that the compositional G films has better mechanical properties compared with those of the PG and SG films in both the dry and wet states. (c) 2007 Wiley Periodicals, Inc.