Polymer membranes plasticization

Semenova SI, Smirnov SI, and Ohya H. Performances of glassy polymer membranes plasticized by interacting penetrants. J Membr Sci 2000 172 75-89. 

These compounds form neutral inclusive complexes, in particular with compounds containing aromatic and heterocyclic groups, which allows applying them as iono-phores. In a polymer membrane plasticized with o-NPOE, lipophilic additives were also placed, in order to ensure the electroneutrality of the membrane. The electrode also shows a Nernstian response in the range of ibuprofen concentration of 10 -10 mol L, low detection limit of 3 x 10 mol Land good selectivity. The precise and reproducible measurement data for ibuprofen determination in water samples and pharmaceutical preparations, Brufen and Ratiopharm (from a local drug store), 96% on average, support its analytical usefulness. 

An electrode was developed that can be used for determination of indomethacin analog—sulindac [83]. Sulindac is less toxic compared to indomethacin, but its action is weaker [83]. The electrode was prepared according to BMSA design. Its polymer membrane plasticized with DBP contains an associative complex of sulindac tetraocty-lammonium (Z)-5-fluoro-2-methyl-1 -[ [p-(methylsulfinyl)phenyl]methylene]-1 H-in-dene-3-acetate (TOA-SUL). The electrode functions correctly in the concentration range of 5 x 10" -1 x 10" mol with a slope of 57.5 1.6 and the detection limit of 1.4x10 mol L 4n a pH range of 6.0-9.0. The sensor can be used for 3 months. 

The preparation and properties of a novel, commercially viable Li-ion battery based on a gel electrolyte has recently been disclosed by Bellcore (USA) [124]. The technology has, to date, been licensed to six companies and full commercial production is imminent. The polymer membrane is a copolymer based on PVdF copolymerized with hexafluoropropylene (HFP). HFP helps to decrease the crystallinity of the PVdF component, enhancing its ability to absorb liquid. Optimizing the liquid absorption ability, mechanical strength, and processability requires optimized amorphous/crystalline-phase distribution. The PVdF-HFP membrane can absorb plasticizer up to 200 percent of its original volume, especially when a pore former (fumed silica) is added. The liquid electrolyte is typically a solution of LiPF6 in 2 1 ethylene carbonate dimethyl car-... 

The optical sensors are composed of ion-selective carriers (ionophores), pH indicator dyes (chromoionophores), and lipophilic ionic additives dissolved in thin layers of plasticized PVC. Ionophores extract the analyte from the sample solution into the polymer membrane. The extraction process is combined with co-extraction or exchange of a proton in order to maintain electroneutrality within the unpolar polymer membrane. This is optically transduced by a pH indicator dye (chromoionophore)10. 

Polymer-based pH sensors are not suitable for continuous in-vivo measurements due to the poor biocompatibility of plasticizers used in the polymer membrane. To minimize such a problem, surface treatment or using a reduced amount of plasticizers has been proposed [71]. In order to improve stability and adhesion, polyurethane has been used as an alternative to PVC membranes in the construction of pH sensing membranes [72, 73],... 

Shvedene, N.V., Chernyshov, D.V., Khrenova, M.G., Formanovsky, A.A., Baulin, V.E., and Pletnev, I.V., Ionic liquids plasticize and bring ion-sensing ability to polymer membranes of selective electrodes, Electroanal., 18,1416-1421, 2006. 

In some cases, conducting polymer-based ion-selective membranes can substitute the commonly used plasticized PVC-based ion-selective (liquid) membranes. However, there are fundamental differences between the two types of membranes. Conducting polymer membranes are most often non-plasticized and the charge is transported by both... 

The use of ISEs with ion-selective membranes based on plasticized PVC, as well as glass pH electrodes, is limited to the analysis of aqueous solutions. On the other hand, sensors based on conducting polymer membranes are usually insoluble in organic solvents, which extends the range of possible applications. Electrosynthesized polypyrrole doped with calcion works as a Ca2+ sensor that can be applied as indicator electrode in the titration of Ca2+ with NaF in mixed solvents, such as water-methanol (1 1) and water-ethanol (1 1) [52], Another example is the use of polyaniline as indicator electrode in order to follow the acid-base precipitation titration of trimeprazine base with tartaric acid in isopropanol solution (see Procedure 5). 

D.R. Paul, Diffusive Transport in Swollen Polymer Membranes, in Permeability of Plastic Films and Coatings, H.B. Hopfenberg (ed.), Plenum Press, New York, pp. 35-48 (1974). 

When the gas or vapor feed stream contains a component that is highly soluble in the polymer membrane and causes plasticization, then the selectivity as defined by Equation 4.6 will depend on the partial pressure or the amount of the plasticizing component sorbed into the membrane. Furthermore, pure-gas permeation measurements are generally not a good indicator of the separation performance, and mixed-gas permeation measurements will be needed [21-23]. Often, the mixed-gas selectivity is less than predicted from pure-gas measurements [8] however, the opposite has been observed [24], Competitive sorption effects can also compromise the prediction of mixed-gas behavior from pure-gas measurements [25], For gas pairs where each component is less condensable than C02, like 02/N2, it is generally safe to conclude that the selectivity characteristics can be accurately judged from pure-gas permeabilities at all reasonable pressures. When the gas pair involves a component more condensable than C02, plasticization is likely to be a factor and pure-gas data may not adequately reflect mixed-gas selectivity. When C02 is a component, the situation depends on the partial pressures and the nature of the polymer. 

Proton exchange membrane (pem) fuel cells, also known as polymer electrolyte membrane fuel cells, have a plastic electrolyte. The membrane material most widely used in pems is produced by DuPont and looks like the plastic wrap used for storing foods. The word proton refers to the hydrogen ion that passes through the polymer membrane. 

Hassan and Rizk developed potentiometric dipyridamole sensors based on lipophilic ion-pair complexes and native ionic polymer membranes [18]. The sensors are based on the use of the ion-association complexes of dipyridamole cation with tetraphenylborate and reineckate counteranions as ion-exchange sites in plasticized PVC matrices. A plasticized native polymer (carboxylated polyvinyl chloride) can also be used. These sensors exhibit linear and near-Nernestian responses for 10 mM-1 pM... 

Polymers containing plasticizing solvents. Addition of solvents such as EC or PC to the polymeric systems of the types shown in Table 10 improves their conductivity considerably. Of special importance are conducting polymeric membranes based on polyacrylonitrile (PAN) containing EC, PC, and Li salts such as LiC104, LiS03CF3 [382],... 

When the interaction between one penetrant and the polymer is not affected by the presence of another penetrant, the pure-component permeabilities of the two penetrants in the mixture can be used in Equation 7. For rubbery polymers at low penetrant partial pressures, this assumption of independent-permeation appears satisfactory (19-20). It does not, however, appear to hold in general for glassy polymer membranes (12,13,21-25). Moreover, it also has been shown that plasticization of both rubbery (26) and glassy (27) polymers can occur at higher penetrant activities. 

In commercial electrodes, the liquid ion-exchanger is in a form in which the chelating agent is immobilized in a hydrophobic polymer membrane like poly(vinylchloride) (Pig-ure 2.4.4). Electrodes based on this design (called polymer or plastic membrane ISEs) are more rugged and generally offer superior performance. 

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