PHOTOREVERSIBLE POLYMERIC MEMBRANES

A variety of advances have been made in the use of environmental facto rs to control the separation characteristics of polymeric membranes in real time. These systems work by incorporating membrane materials whi ch respond to external stimuli such as temperature or pH by making cha nges in conformation, solubility, or phase. In this review we focus on the use of light (photons) as the external control stimulus. Specific ally, we examine the ability to control polymeric membrane properties by incorporating reversible photochromic moieties into the polymer str ucture. The first section is a brief review of the chemistry of photoc hromic compounds, the second section focuses on photocontrol of the se paration properties of nonporous and hydrogel membranes, and the third section discusses the photocontrol of release rates from synthetic bi layer membranes.