Polyvinyl Chloride Composite Membranes Made with Nafion and Polysiloxanes for Use in Electrochemical Breath Alcohol Sensors

Two polyvinyl chloride (PVC) composites were synthesized and tested for their performance in an electrochemical ethanol sensor device. A PVC-Nafion composite was synthesized by imbuing a porous freestanding PVC membrane with a Nafion solution and allowing the Nafion to cast within the PVC. A PVC-sulfonated silica composited was also synthesized by first allowing a sol-gel reaction to take place between tetraethylorthosilicate (TEOS) and 3-(trihydroxysilyl)-1-propanesulfonic acid (TPS). A PVC membrane was then imbued with this solution and the sol-gel reaction was allowed to finish within the PVC membrane. The membranes were characterized with FTIR and TGA to confirm the presence of the additives to the PVC membrane. The PVC-Nafion composite was found to show extremely poor performance in a sensor role, due to the Nafion blocking the pores to allow for adequate ionic transport within the PVC film. The PVC-sulfonated silica showed comparable performance to the freestanding PVC, but using 75% less water to achieve the similar results. This has the advantage of being less prone to leaching and flooding, which has significant advantages in a sensor application role.