Biomedical membranes from hydrogels and interpolymer complexes

Biomedical applications of hydrogel membranes require understanding of their structural characteristics and diffusive behavior. Thus, the subject of this review is the analysis of the response of such biomembranes to their surrounding environment. This responsive behavior may be due to the presence of certain functional groups along the polymer chains or specific interactions between polymer chains (complexation). This behavior is particularly important in the use of these physiologically responsive materials in membrane applications. We begin with an introduction to the structural characteristics and behavior of hydrogel membranes followed by a discussion of the types of environmentally responsive behavior seen with hydrogels. The subject of interpolymer complexation is then treated with emphasis on complexation due to hydrogen bonding and how this type of behavior may be used to produce responsive membranes. Finally, the theories of transport in membranes are reviewed.