SOME EFFECTS OF REDUCING THE CHARGE-DENSITY ON THE TRANSPORT-PROPERTIES OF SULFONATED POLY(ETHER ETHER SULFONE) POLY(ETHER SULFONE) MEMBRANES/

Sulfonated poly(ether ether sulfone)/poly(ether sulfone) copolymer mem branes can be made with a range of densities of sulfonic acid cation e xchange groups. Measurements of membrane potentials enable the transpo rt number of cations (in our case sodium ions) in the membranes to be obtained. The conductances of these membranes have also been measured. It is clear that the nature of the transport behavior changes as the cation density decreases. For the most ''dilute'' membrane the transpo rt number seems not to obey Donnan theory. The conductance of that mem brane is about five orders of magnitude less than the most ''concentra ted'' membrane whose charge density is less than four times as great.