Poly matrix membrane

R. Yuan, Y.Q. Chai, and R.Q. Yu, Poly(vinyl chloride) matrix membrane pH electrode based on 4,4 -bis[(N,N-diakylamino)-methyl]azobenzene with a wide linear pH response range. Analyst 117, 1891-1893 (1991). 

Up to now, a variety of non-zeolite/polymer mixed-matrix membranes have been developed comprising either nonporous or porous non-zeolitic materials as the dispersed phase in the continuous polymer phase. For example, non-porous and porous silica nanoparticles, alumina, activated carbon, poly(ethylene glycol) impregnated activated carbon, carbon molecular sieves, Ti02 nanoparticles, layered materials, metal-organic frameworks and mesoporous molecular sieves have been studied as the dispersed non-zeolitic materials in the mixed-matrix membranes in the literature [23-35]. This chapter does not focus on these non-zeoUte/polymer mixed-matrix membranes. Instead we describe recent progress in molecular sieve/ polymer mixed-matrix membranes, as much of the research conducted to date on mixed-matrix membranes has focused on the combination of a dispersed zeolite phase with an easily processed continuous polymer matrix. The molecular sieve/ polymer mixed-matrix membranes covered in this chapter include zeolite/polymer and non-zeolitic molecular sieve/polymer mixed-matrix membranes, such as alu-minophosphate molecular sieve (AlPO)/polymer and silicoaluminophosphate molecular sieve (SAPO)/polymer mixed-matrix membranes. 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Another type of mixed-matrix membranes for alcohol/water pervaporation applications was developed utilizing hydrophiUc poly(vinyl alcohol) (PVA) and ZSM-5. The ZSM-5/PVA mixed-matrix membranes demonstrated increased selectivity and flux, compared to pure PVA, for the water/isopropyl alcohol separation [97]. This type of mixed-matrix membranes, however, may have membrane swelling issue due to the hydrophilic nature of the PVA polymer. Mixed-matrix membranes comprising modifled poly(vinyl chloride) and NaA zeolite have shown both enhanced flux and selectivity for the ethanol/water separation at high NaA loadings [98]. 

Mahajan, R., Bums, R., Schaefer, M., and Koros, W.J. (2002) Challenges in forming successful mixed matrix membranes with rigid polymeric materials. /. Appl. Poly. Sci., 86, 881-890. 

G. J. Moody and J. D. R Thomas, Poly(vinyl chloride) matrix membrane ion-... 

Hamada et al. used a poly (vinyl chloride) matrix membrane ion-selective electrode for the analysis of procaine [76]. Procaine flavianate (10 mg, prepared by precipitation from an equimolar mixture of procaine hydrochloride and flavianic acid), was mixed with PVC powder (150 mg), dioctyl phthalate (370 mg), and tetrahydrofuran (4 mL). This mixture was used to produce membranes (3 cm diameter), from which discs were cut to prepare ion-selective electrodes. The electrodes were used in conjunction with a double-junction Ag-AgCl (KNO3) reference electrode for the potentiometric determination of procaine hydrochloride at 25°C. 

Crown ethers [364] have proved to be an excellent choice as ionophores for the fabrication of ion sensors because of their ability to complex selectively a particular ion. The cadmium selective sensors have been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing macrocyclic ionophores benzo-15-crown-5 [365], monoaza-18-crown-6 [366], dibenzo-24-crown-8 [367], dicyclohexano-18-crown-6 [368], 3,4 ll,12-dibenzo-l,6,... 

Khalil, S. Borham, N. Phenothiazine drug poly(vinyl chloride) matrix membrane electrodes and their use in pharmaceutical analysis. Microchem. J. 1999, 63, 389-397. 

Diffusion of Water in poly[PFSA] Membranes To describe diffusion of water through the membrane in the presence of a water activity gradient, an appropriate interdiffusion coefficient must be determined. Experimental methods used to study diffusion of water in these polymers, such as radiotracer and pulsed gradient spin-echo NMR techniques, probe intrad-iffusion coefficients, often referred to as tracer or self-diffusion coefficients, determined in the absence of a chemical potential gradient. Intra- and interdiffusion coefficients are related for the case of diffusion of a small molecule in a polymeric matrix as follows [28] ... 

Moody, G.J. and Thomas, J.D.R., "Poly(vinylchloride) Matrix Membrane... 

Mixed matrix membranes with zeolite as organic particles and polymeric matrices such as poly(vinyl acetate) (PVAc), Ultem , and Matri-mid have been prepared. The selectivity of nitrogen to oxygen nearly reaches a factor of 2 over conventional pure polymeric membranes. PI is superior to PVAc in mixed matrix membranes. This is attributed to a higher intrinsic selectivity of the polymer itself. Aminosilanes can be used as cou-... 

When the polymer permeability becomes too high the selectivity of the mixed-matrix membrane approaches the polymer selectivity. Hence the above equation gives a theoretical estimation of the selectivity of a mixed-matrix membrane and it gives an idea of how the permeability of molecular sieve and poly-... 

When water is used as a medium for CO2 reduction, it is important to suppress proton reduction to produce H2, which is more favorable in water than CO2 reduction. A hydrophobic polymer environment can provide such conditions by suppressing proton reduction to selectively carry out CO2 reduction. In an electrocatalytic CO2 reduction by CoPc confined in a poly(vinylpyridine) membrane coated on an electrode, selective CO2 reduction takes place, producing CO [119]. It is of further interest that in the electrocatalytic system, a third electron is injected into the Co(I)Pc(-3) - CO2 intermediate to produce CO and Co(I)Pc(-2) complex after the starting Co(II)Pc(-2) complex is reduced by two electrons to Co(I)Pc(-3) to form Co(I)Pc(-3) - CO2 with CO2. Such a mechanistic scheme can be represented by Fig. 20 [119]. Path I is the previously accepted scheme, and path II is the proposal of a new two-electron reduction pathway. Note also that for the CO2 reduction, a proton is also involved in an equilibrium process. It was inferred that in the polyvinylpyridine matrix, protonation and deprotonation takes place easily with the help of the pendant pyridine groups in a concerted fashion, resulting in favorable CO production (see also Fig. 20) [119]. 

Kim, S., Pechar, T.W. and Marand, E. 2006. Poly(imide siloxane) and carbon nanotube mixed matrix membranes for gas separation. 192(1-3) 330-339. 

Lue, S.J., Chen, J.Y. and Yang, J.M. 2008. Crystallinity and stabihty of poly(vinyl alcohol)-fumed silica mixed matrix membranes. Q QHjoL ScL 47(1) 39-51. 

The versatility of ISEs was enhanced considerably by the introduction of membranes containing neutral ion carriers (ionophores). The first ISE of this type, with a membrane containing valinomycin and selective for potassium ions, was described by Stefanac and Simon in 1966. There are many liquid chemical systems that interact highly selectively with ions through, e.g., ion exchange, ion association, or solvent extraction. Practically useful ISEs based on these systems and on neutral ionophores have been obtained due to the gradual perfection of the technology of plasticized poly(vinyl chloride) (PVC) matrix membranes. 

J.J. Lu, Z. Zhu, W. Wang, S. Liu, Coupling sodium dodecyl sulfate-capillary polyacrylamide gel electrophoresis with matrix-assisted laser desorption ionization time-of-flight mass spectrometry via a poly(tetrafluoroethylene) membrane. Anal. Chem. 83 (5) (2011) 1784-1790. 

Guan, H.-M., Chung, T.-S., Huang, Z., Chng, M. L., Kulprathipanja, S. (2006). Poly(vinyl alcohol) multilayer mixed matrix membranes for the dehydration of ethanol-water mixture. Journal of Membrane Science, 268, 113—122. 

Figure 5. Calibration curves for the analysis of Na and NHf ions using ion sensor made from bilayer of ferrocene-linked ormosil and dibenzo-18-crown-6 incorporated plasticized poly (vinyl chloride) matrix membrane.

Rafizah WAW, Ismail AF (2008) Effect of carbon molecular sieve sizing with poly(vinyl pyrrolidone) K-15 on carbon molecular sieve-polysulfone mixed matrix membrane. J Membr Sci 307(1) 53-61... 

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