Poly selected polyanion

Additional semipermeable membrane—forming polymers are selected from the group consisting of acetaldehyde dimethyl cellulose acetate, cellulose acetate ethyl carbamate, cellulose dimethylamino acetate, semipermeable polyamides, semipermeable polyurethanes, or semipermeable sulfonated polystyrenes. Semipermeable cross-linked selectively permeable polymers formed by coprecipitation of a polyanion and a polycation also can be used for this purpose.22 23 Other polymer materials such as lightly cross-linked polystyrene derivatives, semipermeable cross-linked poly(sodium styrene sulfonate), and semipermeable poly (vinylbenzyltrimethyl ammonium chloride) may be considered.24,25... 

Moreover, intermacromolecular complex formation is applied to selective recovery of organic and metallic ions. For example, as shown in Table 27, Cu2+ ion is much more effectively precipitated by the polyelectrolyte complex than by one of its components520. Furthermore, polyelectrolyte complexes including some metal ions have been studied in recent years (see Sect. 3.2.). Crown ethers can bind certain cations they especially exhibit high affinity to K+. Smid et al.S21) synthesized poly(vinylbenzo-[18]-crown-6). Such polymers containing crown ether with K+ behave like polycations in solution and can interact with polyanions such as poly(carboxyHc acid) to generate a kind of polyelectrolyte complexes. Moreover, PAA may interact with the ether oxy-... 

Hammond and coworkers [167] prepared several LBL assembled films onto Nafion using different polyanions and polycations. The best results were obtained with a membrane produced assembling poly(ethylene imine) (LPEI) and sulfonated poly(2,6-dimethyl 1,4-phenylene oxide) (sPPO), having k, 47 and a DMFC performance over 50 % compared to unmodified Nafion. Moon and Rhim [168] prepared LBL assembled membranes using poly(allylamine hydrochloride) (PAH) and poly (estyerene sulfonic acid) (PSSA), where both, methanol and conductivity decrease with the number of layers, in such a way that methanol selectivity does not improve significantly in comparison with unmodified Nafion. However, Nafion membranes coated with a layer of PAH exhibit a DMFC performance at 80 °C much better (150 mW.cm ) than Nation (70 mW.cm ) when fed with 5 M methanol. PAH and poly (vinyl sulphate) (PVS) were LBL assembled onto Nafion achieving a reasonable methanol selectivity = 3 ) [170], without test in DMFC. 

Complexation in its various forms plays a key role in the homo- and copolymerization of 1-alky 1-4-vinylpyridinium ions. Intermonomer associations are believed responsible for the enhanced poly-merizability of monomers with long alkyl chains (C , n > 6) on nitrogen, the ability of the title monomers to copolymerize with anionic and Ti-rich monomers, and the strong dependence on concentration for homopolymerization of all these cationic monomers. Hydrophobic interactions between lipophilic monomers, electrostatic attraction between cationic and anionic monomers, and charge-transfer complexation between Ti-rich and Ti-deficient monomers have all been observed to control polymer formation. Monomer organization/orientation on polyanion templates, at organic solvent-water interfaces and in ordered multiple-phase systems such as micelles, membranes, vesicles, and microemulsions have been used with limited success in attempts to control the microstructure (e.g. tacticity, monomer sequence) in the related polymers. Interpolymer complexes of poly(l-alky 1-4-vinylpyridinium ions) with natural and synthetic poly anions represent a rich resource for the development of selective electroanalytical methods, for efficient new separation procedures, for manipulation of biomembranes in drug dehvery, and numerous other applications. 

FIGURE 15.23 Commonly used polyanions for the development of active-selective layer (a) polyfstyrene sulfonate) (PSS) sodium salt (Data from L. Setiawan et al., Desalination, 312, 99-106, 2013.) (b) sulfated chitosan (Data from J. Miao et al., Desalination, 181, 173-183, 2005.) (c) poly(vinyl sulfonic acid) (PVSu) sodium salt (Data from B. Tieke et al.. Advances in Colloid and Interface Science, 116, 121-131, 2005.) (d) poly(vinyl sulfate) (PVS) potassium salt (Data from B. Tieke et al., European Physical Journal E, 5, 29-39, 2001.) (e) poly(methacrylic acid) (PMA) soldium salt (Data from D. Saeki et al.. Journal of Membrane Science, 447, 128-133, 2013.) and (f) poly(acrylic acid) (PAA). (Data from W. Shan et al. Journal of Membrane Science, 349, 268-278, 2010.)... 

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