Polymeric membranes poly ethylene

Continuous homogeneous catalysis is achieved by membrane filtration, which separates the polymeric catalyst from low molecular weight solvent and products. Hydrogenation of 1-pentene with the soluble pofymer-attached Wilkinson catalyst affords n-pentane in quantitative yield A variety of other catalysts have been attached to functionalized polystyrenes Besides linear polystyrenes, poly(ethylene glycol)s, polyvinylpyrrolidinones and poly(vinyl chloride)s have been used for the liquid-phase catalysis. Instead of membrane filtration for separating the polymer-bound catalyst, selective precipitation has been found to be very effective. In all... 

A new polymeric amphiphile based on cationic poly(L-lysine), which was partially modified with hydrophobic palmitoyl chains and hydrophilic neutral methoxy-poly(ethylene glycol) (Fig. 7e), was introduced by Uchegbu et al. [38,39], In water in the presence of cholesterol, these copolymers assembled into vesicles with diameters ranging from 200 to 600 nm (DLS, freeze-fracture TEM), depending on the chemical composition of the copolymer and the length of the polypeptide backbone. More detailed information about the secondary structure of chains and the structure of vesicle membranes were not given. 

Kravets, L., Dmitriev, S., Lizunov, N., Satulu, V, Mitu, B. and Dinescu, G. 2010. Properties of poly(ethylene terephthalate) track membranes with a polymer layer obtained by plasma polymerization of pyrrole vapors. Nucl. Instrum. Methods Phv.[Pg.208]

Li et al. (2008a) introduced solvent-resistant multifunctional PV membranes based on segmented polymer networks (SPNs). Hydrophilic (acrylate)-terminated poly(ethylene oxide) was used as a macromolecular cross-linker of different hydro-phobic polyacrylates for the synthesis of amphiphilic SPNs. Multifunctional canposite membranes with thin SPN top layers were prepared by in situ polymerization. The support consisted of hydrolyzed PAN. These membranes were tested for dehydration of EtOH and isopropyl alcohol. The selectivity of the membranes greatly depended on the composition or the ratio of the hydrophilic and hydrophobic phases of the SPN. 

Ulbricht and Schwarz (1997) applied for the first time the pore-filling heterogeneous graft copolymerization concept to asymmetric membranes. Asymmetric PAN membranes (average pore sizes of 7 or 12 nm) were used as matrix of polymeric PV separation phases, which were prepared in situ by heterogeneous photo-initiated graft copolymerization. By this means, defect-free and stable layers were synthesized from moderately hydrophilic methacrylates such as poly(ethylene glycol methacrylates). 

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