Hydrophilic polymer membranes

HW Osterhoudt. Transport properties of hydrophilic polymer membranes. The influence of volume fraction polymer and tortuosity on permeability. J Phys Chem 78 408-411, 1974. 

Novel hydrophilic polymer membranes based on crosslinked poly(allylamine hydrochloride) (PAA.HCl)-PVA have been developed in order to dehydrate different organic compounds by pervaporation [33], The characteristics of the acetone dehydration process,... 

Copolymers of peptides/proteins having amino groups with acrylonitrile Hydrophilic polymer membranes... 

Hydrophilic polymer membranes have also been developed, which will permeate methanol, ethanol, and to some extent isopropanol. These compounds can be removed from less polar organics, although membrane selectivity is not as high as when permeating water. Fig. 25 shows an industrial vapor permeation plant, which continuously removes methanol from a methyl ester/methanol azeotrope. 

Extensive studies on thermo-osmosis have been carried out using various hydrophobic and hydrophilic membranes [29]. Using non-equilibrium thermodynamic principles, it was concluded that water is transferred through hydrophilic polymer membranes from the cold side to the hot side because the transported entropy of water in the membrane is smaller than molar entropy of water in the external free solutions. In contrast, water is transferred through hydrophobic polymer membranes from the hot side to the cold side because the transported entropy of water in the membrane is larger than the molar entropy of water in the external free solutions. 

Wang, X. R, Shen, Z. Q., Zhang, F. Y, and Zhang, Y. F. 1999. Preferential separation of ethanol from aqueous solution through hydrophilic polymer membranes. J. Appl. Polym. Sci. 73 1145-1151. 

Huang, Y., Ly, J., Nguyen, D., Baker, R. W. (2010). Ethanol dehydration using hydrophobic and hydrophilic polymer membranes. Industrial and Engineering Chemistry Research, 49, 12067-12073. 

In general, hydrophilic polymer membranes such as poly(vinyl alcohol) exhibit low gas permeability under a dry state. For example, the permeability of dry poly(vinyl alcohol) is 5.2 x 10 (cm (STP) cm/cm -... 

Hydrophilic polymer membranes, interaction with cells, 120-1 Hydrophilic polymers, 18, 19... 

Aqueous degreasing processes use alkaline or acid solutions containing chemicals and various additives. These baths become contaminated with oil and when the bath loses its efficiency, its contents have to be renewed, at a high cost, or the oil must be removed. A well tested method for oil removal is based on using CFCC (carbon fibre-carbon composite) filter membranes, and permanently hydrophilic polymer membranes. 

Hydration of polymeric membranes may be influenced by the chemical identity of the polymers. A hydrophilic polymer has a higher potential to hydrate than a hydrophobic one. Sefton and Nishimura [56] studied the diffusive permeability of insulin in polyhydroxyethyl methacrylate (37.1% water), polyhydroxy-ethyl acrylate (51.8% water), polymethacrylic acid (67.5% water), and cupro-phane PT-150 membranes. They found that insulin diffusivity through polyacrylate membrane was directly related to the weight fraction of water in the membrane system under investigation (Fig. 17). 

Fig. 9.18 The polymer spacer concept for the construction of a biomimetic cell membrane on solids. Mesogenic units, coupling groups and the flexible polymer can be combined either in form of a statistical terpolymer (above). Variation of the ratio of the three monomers allows an easy tuning of the system. In an alternative system, an end-functio-nalized linear hydrophilic polymer chain bearing a coupling group at the proximal and the mesogen at the distal end was employed.

Nondegradable polymers are also useful as matrices for ocular implants. This application requires the polymer to be hydrophilic, to minimize local tissue irritation. Need for ocular implants stems from the challenges posed to conventional ocular medicines (i.e., eye drops) such as rapid dilution, tear washout, poor patient compliance, and limited bioavailability. Ocular implants from hydrophilic polymer matrices that provide localized sustained release may overcome the above limitations. The first polymeric sustained release product to reach the market was Ocusert , a pilocarpin sustained release ocular implant developed by Alza. Ocusert has the drug reservoir as a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of microporous membrane fabricated from ethylene-vinyl acetate copolymer. The microporous membranes permit the tear fluid to penetrate into the drug reservoir compartment to dissolve pilocarpine from the complex. Pilocarpine molecules are then released at a constant rate of 20 or 40 pg/hr for a four- to seven-day management of glaucoma. 

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