Vapor permeation membranes composite polymer

In pervaporation and vapor permeation processes the permeate leaves the membrane as a vapor, hence the driving force for permeation for a particular component is the difference in partial vapor pressure of that component across the membrane. The partial vapor pressures of the components at the feed side are fixed by the feed composition and temperature. Temperature can only be increased up to the operating limit of the membrane material, typically quite low for polymer membranes. Therefore, the driving force for the transport of matter through the membrane is applied principally by reducing the partial vapor pressure at the permeate side. 

Yoon el al. [112] reported an all-solid-state sensor for blood analysis. The sensor consists of a set of ion-selective membranes for the measurement of H+, K+, Na+, Ca2+, and Cl. The metal electrodes were patterned on a ceramic substrate and covered with a layer of solvent-processible polyurethane (PU) membrane. However, the pH measurement was reported to suffer severe unstable drift due to the permeation of water vapor and carbon dioxide through the membrane to the membrane-electrode interface. For conducting polymer-modified electrodes, the adhesion of conducting polymer to the membrane has been improved by introducing an adhesion layer. For example, polypyrrole (PPy) to membrane adhesion is improved by using an adhesion layer, such as Nafion [60] or a composite of PPy and Nafion [117],... 

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