The Electrical Properties of Synthetic Membranes

By the addition of n-butyl bromide to a 1:19 copolymer of 4-vinylpyridine and styrene, water-insoluble, strong polyelectrolytes can be prepared. The addition of a hydrocarbon plasticizer permits the casting of flexible films in which large polycations are immobilized but in which bromide ions (or other small anions) are free to move. Electrical measurements on these membranes showed that they could be represented by a complex admittance: an electrolytic conductance in parallel with a pure A. C. impedance. The latter gives a circular arc when real component is plotted against imaginary. These synthetic membranes thus resemble in their electrical behavior that found by Cole for a variety of biological membranes.