Polyelectrolytes preparation

R.B. Hodgdon, Jr., Polyelectrolyte prepared from perfluoroalkylaryl macromolecules,... 

On account of the domain selectivity of sulfochlorination, the derived PE sulfonates should be regarded as block copolymers, i.e. polyelectrolytes with polyalkane and sulfonated polyalkane alternating sequences of various segmental lengths. This is in contrast to the polyelectrolytes prepared by copolymerization (Section II), where randomization along the chain is possible. 

To find out the stabilization effect of polyelectrolytes, silver nanoparticles coated with PAH or PEG at concentrations either 1 mg/ml or 5 mg/ml were examined in 0.5 M NaCl, 0.1 M NaCl or 0.01 M NaCl by UV-Vis spectroscopy. For each type of polyelectrolytes prepared at the concentration of 1 mg/ml independently from their molecular weight and sodium chloride concentration the UV-Vis measurement data revealed most broad absorption bandwidth. The narrow absorption bandwidths were related to both PAH (15 kDa) and PEG (8 kDa) at the same concentration 5 mg/ml in 0.01 M NaCl. Silver nanoparticles modified with 5 mg/ml PAH and 5 mg/ml PEG in 0.1 M NaCl presented narrow absorption widths and relatively high absorbance intensity. Furthermore, PEG coated silver nanoparticles revealed better UV-Vis absorption results among mentioned polyelectrolytes. 

Carrageenans are anionic polyelectrolytes prepared from red seaweed. There are three types k- (kappa), i- (iota), and 1- (lambda) carrageenan commercially available (Figure 26.3). 

KoscheUa A., Heinze X, Novel regioselectively 6-functionalized cationic cellulose polyelectrolytes prepared via ceUulose sulfonates, Macromol Biosci, 1, 2001, 178-184. 

Figure 22.28 and Figure 22.29 show, respectively, the H and C-NMR spectra of the oligoesters prepared from epoxidized sunflower oil methyl esters (methyl biodiesel from sunflower oil) and di-l,2-cyclohexanedicarboxylic anhydride using triethylamine as initiator. These materials are soluble in common organic solvents such as acetone, ethanol, tetrahydrofurane, and chloroform, but insoluble in water. Oligoesters from epoxidized biodiesel can be used as intermediate materials for the synthesis of polyelectrolytes by saponification reactions with aqueous solution of sodium or potassium hydroxide at room temperature (Fig. 22.27). The products obtained after saponification present solubility in water. Amphiphilic materials, such as the polyelectrolytes prepared from epoxidized biodiesel, have hydrophobic and hydrophilic segments. They can spontaneously self-organize in a wide variety of structures in aqueous solution. Understanding the dynamics of the formation and transition between the various self-organized structures is important for technological applications.

Insoluble polyelectrolytes prepared from SMA resins have been explored for waste water purification. Materials of this nature have been shown to be useful to purify waste water from poly(styrene plants) " and possible isolation... 

Crosslinked polyelectrolytes prepared from Gantrez resins exhibit the attractive property of being useful for detection of viruses present in natural or sewage water.The viruses are absorbed at pH 5.0-6.0, concentrated, and eluted for detection at pH 8.0-9.0. 

The starting anionically polymerized polystyrene usually employed is a commercial homopolymer purchased either from Dow Chemical (Styron 666, Mw/Mn = 2.05), from Pressure Chemical and Co. or from Polymer Laboratory Ltd. (Mw/Mn = 1.05). The sulfonation reaction is monitored in order to avoid a complete sulfonation as in the polyelectrolyte preparation. The most commonly employed reaction is performed in 1,2-dichloroethane at 50 °C using acetyl sulfate as sulfonating agent [41]. The sulfonate content is determined after reaction and purification. The polymer molecular weight ranges from 3500 to 1800000 and the sulfonate content from 0 to 10%. The nonpolar solvents commonly used are THF, toluene, xylene or low polarity solvents like cyclohexanone. The conditions of preparation and the aging of the samples were shown to be important parameters [28, 42]. 

Polymer electrolytes incorporating an IL can be classified into two main groups (i) ion gels whereby the IL is the main conducting medium and the polymer is the support and (ii) polyelectrolytes prepared via the... 

Poly(arylene vinylenes). The use of the soluble precursor route has been successful in the case of poly(arylene vinylenes), both those containing ben2enoid and heteroaromatic species as the aryl groups. The simplest member of this family is poly(p-phenylene vinylene) [26009-24-5] (PPV). High molecular weight PPV is prepared via a soluble precursor route (99—105). The method involves the synthesis of the bis-sulfonium salt from /)-dichloromethylbenzene, followed by a sodium hydroxide elimination polymerization reaction at 0°C to produce an aqueous solution of a polyelectrolyte precursor polymer (11). This polyelectrolyte is then processed into films, foams, and fibers, and converted to PPV thermally (eq. 8). 

Substituted PPVs have been prepared using similar techniques. The earliest reports described methyl substituents (104,105), and more recentiy alkoxy substituents on the aromatic ring have been incorporated into the polymer stmctures (107—109). The advantage of long-chain alkoxy (butoxy or hexyloxy) substituents is that not only is the precursor polyelectrolyte soluble, but after conversion the substituted PPV is also soluble (110—112). 

The preparation of molecular composites by electropolymeriza tion of heterocycles in solution with polyelectrolytes is an extremely versatile technique, and many polyelectrolyte systems have been studied. The advantages of this method include the use of aqueous systems for the polymerization. Also, the physical and mechanical properties of the overall composite depend on the properties of the polyelectrolyte, so material tailorabiUty is feasible by selection of a polyelectrolyte with desirable properties. 

Low temperature sol-gel technology is promising approach for preparation of modified with organic molecules silica (SG) thin films. Such films are perspective as sensitive elements of optical sensors. Incorporation of polyelectrolytes into SG sol gives the possibility to obtain composite films with ion-exchange properties. The addition of non-ionic surfactants as template agents into SG sol results formation of ordered mechanically stable materials with tunable pore size. 

The Zincke reaction has also been adapted for the solid phase. Dupas et al. prepared NADH-model precursors 58, immobilized on silica, by reaction of bound amino functions 57 with Zincke salt 8 (Scheme 8.4.19) for subsequent reduction to the 1,4-dihydropyridines with sodium dithionite. Earlier, Ise and co-workers utilized the Zincke reaction to prepare catalytic polyelectrolytes, starting from poly(4-vinylpyridine). Formation of Zincke salts at pyridine positions within the polymer was achieved by reaction with 2,4-dinitrochlorobenzene, and these sites were then functionalized with various amines. The resulting polymers showed catalytic activity in ester hydrolysis. ... 

Gamma Radiation Induced Preparation of Polyelectrolytes and Its Use for Treatment of Waste Water... 

The immobilization of enzymes with the formation of insoluble forms is usually intended for the development of specific catalysts for technical purposes. Here, we consider another medico-biological problem of the preparation of insoluble enzymatic systems based on crosslinked polyelectrolytes, used in the replacement therapy for oral administration. 

Preparative Selective High-Capacity Ion-Exchange Chromatography of Biologically Active Compounds on Crosslinked Polyelectrolytes (Biosorbents)... 

Photoresponsive polyelectrolytes tethered with a photochemical functional group were first reported in 1964 by Lovrien and Waddington [24] who prepared copolymers of iV-azobenzeneacrylamide and acrylic or methacrylic acid (1). 

Sassoon and Rabani [79] also prepared a two polymer system in which a chromophore was covalently bound to one polyelectrolyte and a donor or acceptor was electrostatically held by the other polyelectrolyte, and showed that its back ET underwent a similar retardation effect. They employed 26 as a photosensitizer, MV2+ as a mediator, and ferricyanide as an acceptor electrostatically bound to the added polycation (polybrene). 

As has been described in Chapter 4, random copolymers of styrene (St) and 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) form a micelle-like microphase structure in aqueous solution [29]. The intramolecular hydrophobic aggregation of the St residues occurs when the St content in the copolymer is higher than ca. 50 mol%. When a small mole fraction of the phenanthrene (Phen) residues is covalently incorporated into such an amphiphilic polyelectrolyte, the Phen residues are hydrophobically encapsulated in the aggregate of the St residues. This kind of polymer system (poly(A/St/Phen), 29) can be prepared by free radical ter-polymerization of AMPS, St, and a small mole fraction of 9-vinylphenanthrene [119]. 

For the preparation of spray-dried polyelectrolyte complexes, the polyanion was dissolved in dilute NH4HCO3 solution and mixed with the chitosan carbamate solution just before spray-drying. The excess NH4HCO3 decomposed thermally between 60 and 107 °C on the other hand, the carbamate function released carbon dioxide under the effect of the temperature at which the spray-drier was operated, thus regenerating chitosan at the moment of the polyelectrolyte microsphere formation (Fig. 5). 

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