CHEMICALLY AND ELECTRICALLY CONTROLLED MEMBRANES: SIZE SPECIFIC TRANSPORT OF FLUORESCENT SOLUTES THROUGH PMMA MEMBRANES.

This paper focuses on the use of crosslinked, polyelectrolyte hydrogel membranes to achieve real time control of the flux of charged or neutral solutes by chemical or electrical means. For this purpose, a sensitive system capable of measuring the transmembrane flux of fluorescent solutes was developed, together with a family of fluorescent solutes of various sizes and electrical charge. Experimental results shown that large, reversible, size-specific permeability changes can be induced in crosslinked poly(methacrylic acid) (PMAA) membranes in response to changes in bath composition and to applied electric currents. The data show that permeability changes as high as a factor of 50 can be induced by altering the bath pH surrounding crosslinked PMAA membranes. Applications are in the area of actively controlled time variable membrane separation and drug delivery systems, as well as low energy analytical and preparative systems.