Polystyrene and polyvinylpyridine

Numerous examples of these systems have been studied experimentally. Tirrell et ah measured the adsorption of AB copolymers of polystyrene and polyvinylpyridine on mica. A wide range of molecular weights was tested, and it was found that, for most samples, about 200 ng/cm of polymer adsorbed to the surface, and that the buoy segments easily formed polymer combs , unless the size of the anchoring segment was too large. The maximum surface density was found with small... 

This method was applied to synthesize various networks, with elastic chains of different nature polystyrene, polymethacrylates, polyvinylpyridine, and more recently polydienes. In some cases ethylene dimethacrylate is used to achieve cross-linking9, because of its higher electrophilicity. 

In addition to recent advances in block co-polymer templating of periodic mesoporous silica and silica colloidal crystal templating of periodic mesopo-rous polymers [79], SAMs have been used for polymer patterning [80]. Mixtures of two strongly incompatible polymers, a polystyrene (PS)-polyvinylpyridine (PVP) blend, were found to phase separate when placed on a... 

Monosized spherical polystyrene latex particles of diameter 1.73 yarn and polyvinylpyridine of molecular weight equal to 589,000 were employed, for which C is equal to 3.06 g/L. The experiments were carried out at pH 3.0 and 25°C. 

An alternative strategy, which utilizes micelle-forming amphiphilic block copolymers in the stabilization of metal nanoparticles, has been extensively studied and can be described as nanoreactors as the metal colloids are synthesized within their interior. This has enabled the formation of nanosized (l-2nm) metal colliods or clusters within polystyrene-Z -polyvinylpyridine (PS- -PVP) micellar assemblies, with diameters around 30 mn, and these... 

Mogi et al. [138] and Gido et al. [143] studied triblock terpolymers based on polystyrene (S), polyisoprene (I), and poly(2-vinylpyridine) (VP) with different block sequences. The difference in block sequence resulted in a different morphology for a similar overall composition of the systems. While polyisoprene-block-polystyrene-block-polyvinylpyridine I-S-VP with similar amounts of all three components forms lamellar stacks (Figure 4(a)) [138], polystyrene-block-polyisoprene-block-polyvinylpyridine S-I-VP forms hexagonally packed core-shell cylinders (Figure 4(b)) [143]. 

Polymer bilayer systems such as polyvinylpyridine-polystyrene and polystyrene-poly(methylmethacrylate) were investigated by XR. It was demonstrated that the interfacial parameters can be determined with high accuracy although the difference in the electron densities (the contrast) of the two polymers are extremely small. 

We have conducted the comparative study of gold (III), platinum (IV) and palladium (II) acidocomplexes solution on macroporous granular sorbents on the basis of polystyrene with functional groups of methyleneamine, 3-methylpyrasolyl, N,N-dimethylaminomethylene, dimethylmethylene-P-oxyethylamine and with functional 6-(3-methylpyridine) groups on polyvinylpyridine basis as well as fibrous polystyrene sorbent with pyrazolyl groups. 

The capacity of studied organopolymeric sorbents depends on metal nature (Pd (II) > Au (III) > Pt (IV)) as well as on the composition and stmcture of sorbent matrix (polyvinylpyridine macroporous > polystyrene macroporous > polystyrene fibrous). 

The polyelectrolyte systems studied were sodium polystyrene sulfonate (NaPSS) (with sodium nitroanilinsulfonate being the inert salt) and some of the quaternized polyvinylpyridines listed in Table 2 (with Basic Blue 1=2-chloro-4, 4"-bis-dimethylamino-tritylium chloride being the inert salt). The PVP was quaternized to an extent of 60%, i.e. the reduced charge density is =1.7, while the PSS was sulfonated to an extent of 80%, hence =2.3. 

Oxidation of secondary alcohols with catalyzed by methyltrioxorhenium (MTO) as homogeneous catalyst and supported MTO (polyvinylpyridine/MTO and polystyrene/MTO) as heterogeneous catalysts was investigated by Crucianelli et al. [3]. 

A rapid initial drop in molecular weight followed by a slower decrease is observed when polyvinylpyridine is heated at 250°C [85]. This behaviour is qualitatively similar to that of polystyrene. Scission of weak links may be involved in the fast decay of molecular weight, but random scission may also explain the shape of the curve. As in the case of polystyrene, the mechanistic problem is very complex and many more experiments are needed to solve it. Chelation of 2- and 4-polyvinylpyridine makes those polymers less heat-resistant chain scissions already occur at 100°C while the uncomplexed polymer suffers no damage at this temperature. On heating, a change in the absorption spectrum of 2-polyvinylpyridine copper chelate dissolved in 1M HC1 is observed a new peak is formed at... 

YIELD OF CROSSLINKING OF POLYVINYLPYRIDINE (PVP) AND POLYSTYRENE IRRADIATED AT ROOM TEMPERATURE [340]... 

Choice of Support. The most commonly used organic support is polystyrene (cross-linked with DVB) in its microp-orous (1-2% cross-linking) form, although it has also been used in its macroporous and popcorn form (Ford et al, 1982 Shan et al.,1989). Various other polymeric catalysts have been used like polyvinylpyridine resins, commercial ion-exchange resins (Arrad and Sasson, 1989), modified dextran anion exchangers (Kise et al, 1981), and macroporous glycidyl methacrylate-ethylene dimethacrylate resins (Hradil and Svec,... 

Another way to functionalize the surface of microlatex particles is to incorporate amphiphilic block copolymers (for example, polystyrene/polyvinylpyridine) as cosurfactants together with the classical surfactants used in the formulation [86,87]. The protruding polyvinylpyridinium chains are anchored to the glassy core through the polystyrene blocks. These blocks copolymers were shown to stabilize the oil/water interface and to effectively bind ions of transition and heavy metals via complexation. 

Finally comments are necessary on a general feature of the polyelectrolyte catalysis. As stated in the introductory part, high molecular weight compounds are more efficient in accelerating chemical reactions under appropriate conditions. It should be noted that this statement is not always justified. For example, polyvinylpyridine is less efficient than 4-picoline in enhancing the solvolysis of dinitrophenyl acetate [62], whereas this polymer is extremely efficient compared to 4-picoline for the solvolysis of 5-nitro-4-acetoxysalicylic acid. Imidazole was 50 times more efficient than polyvinylimidazole in the formation of N-acyl compounds of p-nitrophenyl acetate in dimethylformamide [63]. In the hydrolyses of butylacetate and propyl-acetate, dodecyl benzenesulfonic acid was 6 and 3 times more eflScient than polystyrene sulfonate, respectively [64]. 

When considering typical organic polymers, for example, based on polystyrene, polyethyleneimine, polymethacrylic acid, polyvinylpyridines, polyvinylimi-dazoles, and others, the mainchain of these polymers can be linear or crosslinked. In several cases, a metal is part of the polymer chain leading to new structural imits. Inorganic macromolecules like silica, different kinds of sol-gel materials, and molecular sieves can also be included if these macromolecules are modified in such a way to carry as active part one metal component employing different kind of bonds. 

For preparation of the novel type of SIRs, two types of resins were proposed (1) divinylbenzene (DVB)-cross-linked polyvinylpyridine resins, and (2) conventional anion exchange resins with cross-linked polystyrene skeleton bearing strong basic quaternary amine or weak basic tertiary amine groups. Their properties are summarized in Table 9.2. 

---