Potentiometric response of poly(vinyl chloride)/crown ether membranes to non-ionic alcohols

The membrane potential of plasticized poly(vinyl chloride) membrane doped with crown ether was induced in response to non-ionic alcohols including 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol, in spite of their electrically neutral nature. The magnitude of the potential changes was in the order of 1-octanol> 1-heptanol> 1-hexanol> 1-pentanol> 1-butanol. The potentiometric response of the membrane did not depend on the concentration gradient of Na⁺ ions across the membrane. These results suggest that the changes in surface potential, which arise from the specific adsorption of alcohols to the membrane surface through hydrophobic interaction are responsible for the membrane potential changes.