Organic ionic membranes

Results of numerous items of research have shown that, in theory, any material can be used in the design of a gas sensor, regardless of its physical, chemical, structural, or electrical properties (Korotcenkov 2010,2011). Prototypes of gas sensors based on covalent semiconductors, semiconducting metal oxides, solid electrolytes, polymers, ionic membranes, organic saniconductors, and ionic salts have already been tested (Sadaoka 1992 Gopel 1996 Haugen and Kvaal 1998 Monkman 2000 Talazac et al. 2001 Eranna et al. 2004 Adhikari and Majumdar 2004). As shown in Table 1.23, these materials may be used... 

Phospholipids are found widely in both plant and animal tissues and make up approximately 50% to 60% of cell membranes. Because they are like soaps in having a long, nonpolar hydrocarbon tail bound to a polar ionic head, phospholipids in the cell membrane organize into a lipid bilayer about 5.0 nm (50 A) thick. As shown in Figure 27.2, the nonpolar tails aggregate in the center of the bilayer in much the same way that soap tails aggregate in the center of a micelle. This bilayer serves as an effective barrier to the passage of water, ions, and other components into and out of cells. 

Saxton, R.J., Robert, J. and Minhas, B.S. 2004. Ionic membranes for organic sulfur separation from liquid hydrocarbon solutions. US 6,702,945. 

Systems formed by trapping into a polymer matrix liquid solutions of lithium salts in aprotic organic solvents, which may be considered as third generation polymer ionic membranes. Typical examples of this class are solutions of lithium salts in propylene carbonate-ethylenecarbonate, PC-EC, mixtures trapped in a polyacrylonitrile, PAN, matrix [36]. 

Membrane phenomena cover an extremely broad field. Membranes are organized structures especially designed to perform several specific functions. They act as a barrier in living organisms to separate two regions, and they must be able to control the transport of matter. Moreover, alteration in transmembrane potentials can have a profound effect on key physiological processes such as muscle contraction and neuronal activity. In 1875, Gibbs stated the thermodynamic relations that form the basis of membrane equilibria. The theory of ionic membrane equilibrium was developed later by Donnan (1911). From theoretical considerations, Donnan obtained an expression for the electric potential difference, commonly known as the membrane potential between two phases. 

Pineri M (1986) Microstructure of organic ionic membranes. ACS Symp Ser 302 159-174... 

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