Poly membranes permeability

Chapman et al. [131] reported the synthesis of poly(ethylene oxide) (PEO) supported dendritic f-BOC-poly(a, c-L-lysines). These dendritic polymers termed as hydramphiphiles formed foams possessing good temporal stability in aqueous solution. Scrimin et al. [132] synthesized a three-directional polypeptide having uses in membrane permeability modulation. Decapeptide fragments were linked to TREN [tris(2-aminoethyl)amine] core. 

The permeability data in Table 7.10 and other data show that the polarity of the substituent group on the polymer backbone (such as poly[bis(phenoxy)phosphazene] or PPOP) has a significant impact on the membrane permeability. The more polar gas (i.e. S02) the more easily it permeates a polar polymer (i.e., m-F-PPOP) and a less polar gas (i.e., CO2) exhibits a lower permeability through a more polar membrane (i.e., SO3-PPOP). This seems to provide a vast opportunity for chemically designing an inorganic polymer membrane for a particular separation application [Peterson et al., 1993]. 

CARRE, Inc. also produces a series of dynamic hyperfiltration membranes on porous metal tubes. The major product is the ZOPA hyperfilter hydrous zirconium oxide-poly(acrylic acid) on porous stainless steel tubes. The hyperfiltration properties of the ZOPA membranes are also listed in Table I. The most attractive properties of the ZOPA membrane are durability at temperatures of at least 100 C, high membrane permeability, and reformation capability. The hydrous zirconium oxide-poly(acrylic acid) membranes provide modest rejection of simple electrolytes. Although the membrane permeability is high compared to most cast reverse osmosis /hyper-... 

A simple method to measure the membrane permeability to specific molecules has been presented by G. Battaglia and coworkers [141], The authors encapsulated highly hydrophilic 3,3, 3//-phosphinidynetris-benzenesulfonic acid (PH) into polyethylene oxidc)-co-poly(butylene oxide) (EB) vesicles and monitored its reaction with 5,5/-dithiobis-2-nitrobenzoic acid (DTNB) penetrating the membrane from the exterior. The reaction rate (amount of the formed product as a function of time after DTNB addition) measured with IJV/Vis was directly correlated to the permeability of the permeating molecule. A comparison of these results with the permeability of egg yolk phosphatidylcholine (PC) vesicles showed that EB membranes have a more selective permeability toward polar molecules than the phospholipids membranes. Also in this case the permeability appeared to depend on the membrane thickness as predicted by Fick s first law. 

A system with interesting properties is the poly(ethylene oxide)-Wock-poly[2-(diethylamino) ethyl methacrylalc -.sfa -[3-(trimclhoxysilyl)propyl methacrylate] (PEO-b-P(DEA-sfaf-TMSPMA)) block copolymer. This self-crosslinkable copolymer formed vesicles which demonstrated pH-tunable membrane permeability [223],... 

H. Braun, F. Decker, K. Doblhofer and H. Sotobayashi, The redox-reaction [Fe(CN)6]3 /4 on electrodes coated with fixed charge polymer films - Observation of membrane permeability modulation by the electrode potential, Ber. Bunsenges. Phys. Chem., 1984, 88, 345-350 S-M. Oh and L.R. Faulkner, Luminescent and redox probes of structure and dynamics in quaternized poly(4-viniylpyridine) films on electrodes, J. Am. Chem. Soc., 1989, 111, 5613. 

Wu HY, Tomizawa K, Matsushita M, Lu YF, Li ST, Matsui H. Poly-arginine-fused calpastatin peptide, a living cell membrane-permeable and specific inhibitor for calpain. NeurosciRes2J003 4T. 131 135. 

J. Pieracci, J. V. Crivello, and G. Belfort. Increasing membrane permeability of UV-modified poly(ether sulfone) ultrafiltration membranes. J. Membr. ScL, 202(1-2) 1-16, June 2002. 

Bowen et al. [40] used sulfonated poly(ether ether ketone) (SPEEK) as an additive in the polysulfone (PSf)/SPEEK/N-methyl-2-pyrrolidone (NMP) system. Membrane characterization was carried out using filtration studies and AEM. Membranes prepared from solutions in the region of polyelectrolyte behavior [41] showed more pronounced and systematic improvement of membrane permeability and salt rejection. A small decrease in pore size and surface roughness was also followed by an increase in SPEEK content. Compared with a - 28.5 mN m adhesion force of a 4 pm silica particle for a SPEEK free PSf membrane, a SPEEK modified membrane showed greatly reduced adhesion of - 0.75 mNm h This, together with the surface smoothening effect, leads to the reduction of membrane fouling when the surface is modified by the addition of SPEEK. 

Pieracci, J., Wood, D.W., Crivello, J.V. and Belfort, G. 2002. Increasing membrane permeability of UV-modified poly(ethersulfone) ultrafiltration membranes. 202 ... 

Kuznetsov et al. (2001) used composite membranes, coated with poly(2-dimethyl-amino ethyl)methacrylate (PDMA) and ladder polyorganosiloxane (LP) onto micro-porous aromatic PAI support and PAN, as PV membranes for separating mixtures of methanol and MTBE. It was noticed that the PAI and PAN supports of the multilayer m branes have opposite effects on the total selectivity. High membrane permeability of the multilayer membranes was attained by virtue of the thinness of the interlayer or coating diffusion layer of PDMA with ultrahigh molecular weight. 

Permeabilization of polymer membranes is increased by ethanol or mixtures of specific organic solvents. For example, a small amount (< 0.5% v/v) of ethanol [92] or mixtures of ethanol and dimethyl sulfoxide (1 1 v/v) [90] in the system has no influence on the membrane permeability of PMOXA-fc-PDMS-fc-PMOXA copolymers, and therefore much higher amounts of solvents are necessary to destabilize the membrane. However, this permeabilization method is not appropriate when bioapplications are intended. Likewise, a copolymer membrane based on poly(ethylene glycol)-fcZock-poly(D,L-laetic-5to/-glycolic acid) (PEG-fc-PLGA), which exhibits 18-fold less permeability to protons than a liposome membrane (based on a mixture of soybean phospholipids and cholesterol) was rendered more permeable for proton diffiision when increasing amounts of 1,4-dioxane (5-20%) were added (Fig. 11.7) [93]. Upon removal of the 1,4-dioxane by dialysis, the proton diffusion returned to... 

In addition to the more conventional membranes, such as those of poly-sulfone and silicone rubber, there has been an exponential growth in the R feD of other membrane materials, such as polyimides and polyaramides. Inorganic or carbon sieving materials can also separate many gases, although their fragility and cost have made them less attractive. Robeson has noted a trade-off between the permeability (productivity) and selectivity (efficiency) of typical polymeric membranes. To transcend this well-known upper-bound trade-off curve and maximize both membrane permeability and... 

First, we consider the experimental aspects of osmometry. The semiperme-able membrane is the basis for an osmotic pressure experiment and is probably its most troublesome feature in practice. The membrane material must display the required selectivity in permeability-passing solvent and retaining solute-but a membrane that works for one system may not work for another. A wide variety of materials have been used as membranes, with cellophane, poly (vinyl alcohol), polyurethanes, and various animal membranes as typical examples. The membrane must be thin enough for the solvent to pass at a reasonable rate, yet sturdy enough to withstand the pressure difference which can be... 

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