N-Vinylimidazole

These examples demonstrate that additives can have a beneficial effect on the entrapped biopolymers. Unfortunately, they are generally not universal. The additives need to be found for individual immobilized biopolymers and that is not so easy to do. For instance, lactate oxidase retained its activity in a silica matrix if the enzyme was taken as a complex with poly(N-vinylimidazole) prior to the immobilization, but the polymer did not stabilize glycolate oxidase [87,114], Its stabilization was observed after an exchange of poly(N-vinylimidazole) for poly(ethyleneimine). This is a decisive disadvantage of the approaches because they do not offer a general solution that might be extended to any immobilized biopolymer. 

This strategy was first realized by Lozinsky et al., who studied the redox-initiated free-radical copolymerization of thermosensitive N-vinylcaprolactam with hydrophilic N-vinylimidazole at different temperatures, as well as by Chi Wu and coworkers. Lozinsky presents an extensive review of the experimental approaches, both already described in the literature and potential new ones, to chemical synthesis of protein-like copolymers capable of forming core-shell nanostructures in a solution. 

QPVP = partially quaternized PVP with ethylbromide DBQP = partially crosslinked PVP with dibromobutane PSP = copolymer of styrene and 4-vinyl pyridine PVIm = poly(N-vinylimidazole)... 

In aqueous solvent a hydrophobic environment was constructed by using a water-soluble and hydrophobic tri-block copolymer (Scheme 7). The central block is hydrophobic and composed of the copolymer of styrene and N-vinylimidazole (PSI), to which Cu ions can coordinate. This central block was synthesized by UV-irradia-tion polymerization bytelechelic initiator of bis(4-carbomethoxy-phenyl)-disulfide. The reaction of telechelic block with poly-(ethyleneoxide) gave the block copolymer PE0-PSI-PE0. 

Azole compounds, poly-N-vinylimidazole (PVI-1) and 2-undecylimidazole (UDI), are studied as alternative inhibitors to benzotriazole (BTA) for copper corrosion in aqueous systems using electrochemical techniques. It is shown that UDI, either as a cast film or dissolved in solution at concentrations as low as 7 X inhibits oxygen reduction on... 

N-vinylimidazole (30 g, 0.32 mol) and azobis(lsobutyronltrile) (0.26 g, 0.0016 mol) in benzene (200 ml) was heated at 68°C with stirring under nitrogen for two days. The white precipitated polymer was collected by filtration, washed four times with benzene (20 ml) and dried in a vacuum oven (30 mm Hg) at 40 C for three days. The yield was 30 g (100 conversion). The... 

A set of papers was devoted to the polymerization of N- vinylimidazole in poly(methacrylic acid) matrix. Vinylimidazole is soluble in water and polymerization was carried out in aqueous system using 2,2 -azobis(2-amidopropane)2HCl as initiator ... 

Polymerization of N-vinylimidazole deviates from the polymerization of conventional vinyl polymers such as styrene or methyl methacrylate. The process leads usually to low molecular weight products, which is due to degradative addition. This process can be illustrated by the reaction ... 

Chain transfer to the monomer is discussed by Van den Grampel in connection with polymerization of N-vinylimidazole in the presence of poly(methacrylic acid). Degradative addition by a radical at the 2-position of the imidazole ring can be illustrated by the reaction ... 

Template polymerization can be used for production of polymers with much higher molecular weights in comparison with those obtained by conventional process (in the last case a degradative addition frequently takes place). It was shown based on the example of N-vinylimidazole polymerization. By the template process, polymers with up to 70 times higher molecular weight than in conventional polymerization were obtained. 

Template polymerization based on hydrogen bonded interpolymer complexes has also been studied by Van de Grampel et al. [100]. Crosslinked PMAA networks were used as templates for the polymerization of N-vinylimidazole (Vim) which is known to form complexes with PMAA. The effects of solvent nature on the stability of the PMAA-PNVP complex have been studied by comparing complex stability in aqueous and organic solvents [101], In water, since the hydrophilic carboxylic acid groups of the PMAA were... 

L = polymer-ligand, e.g. FVP = poly(4-vinylpyridine), PVI = poly(N-vinylimidazole) en = ethylenediamine, phen = phenantroline... 

N-Vinylimidazole is a very basic monomer and the basic nitrogen forms a complex with various metal ions. When a metal salt is dissolved... 

Existence of pyrrolidone moiety in the polymer does not always assist in the favorable hydrophobic binding. Poly(N-vinylimidazole-co-N-vinylpyrrolidone), poly(NIM-pr), gives the second order kinetics in the hydrolysis of PNPA(5). 

IM-IM cooperation. It is difficult to establish the IM-IM" cooperation in poly(4(5)-vinylimidazole), since pK2 value is more than 14.5 (74). The IM-IM" cooperation can be observed in hydrolyses of PNPA(5) and 4-acetoxy-3-nitrobenzoic acid [n = 0 in (8)] by poly(5(6)-vinylbenzimidazole), of which pK2 value is estimated to be 12.7 (26). The hydrolyses rates increase sharply as the pH approaches the pK2 value of the polymer. In contrast, such a drastic enhancement in the rate is not observed in the benzimidazole-catalysed hydrolysis, nevertheless, pK2 value of the benzimidazole being 12.7. N-Alkylated polymers such as poly(N-vinylimidazole), poly(NIM), and poly(2-methyl-N-vinylimidazole), poly(2MIM), which have no anionic form in imidazole moieties, show the hydrolytic activities slightly less than that of poly(4(5)-vinylimidazole). In cases of low molecular weight analogues, such as N-methylimidazole and imidazole, the hydrolytic activity of the former is about 75% of the activity of imidazole (75, 76). These phenomena appear to support the IM-IM" cooperation in poly(4(5)-vmylimidazole) indirectly. In the hydrolyses of NABS(l) and NABA(3) by poly(5(6)-vinylbenzimidazole), the activity enhancement is about 50-fold compared with the activity of benzimidazole, in spite of these anionic substrates being used (23, 26). 

It has been attempted to perform template polymer syntheses without using biological sources. Concepts focus on the formation of a complex between monomer molecules and a present macromolecule [4,480], This way the monomer will get preorganized and the polymerization is supposed to follow a zip mechanism controlled by the length and the configuration of the template polymer, offering replication of the molecular weight and control of the stereo structure. Polymerization of acrylic acid in the presence of poly(ethyleneimine), N-vinylimidazole/ poly(methacrylic acid) or acrylonitrile with poly(vinylacetate) have been described [469,470,471,472,473]. Recently the preparation of solid polyelectrolyte complexes from chitosan and sodium-styrenesulfonate has been reported [481]. 

SYNS IH-IMIDAZOLE, 1-ETHENYD, HOMOPOLYMER IMIDAZOLE. 1-VINYL-, POLYMERS LUFIXAN POLY(VINYUMIDAZOLE) POLY(N-VINYUMIDAZOLE) POLY(l-VINYLIMIDAZOLE) Q N-VINYLIMIDAZOLE HOMOPOLYMER N-VINYD IMIDAZOLE POLYMER... 

Polycarbobetaines derived from aromatic or heteroaromatic systems are listed in Scheme 3. The vinylimidazolium betaines 13 and 14 were prepared by alkylation of 1-vinyhmidazole with the corresponding bromocarboxylic acid, and aqueous solution polymerization using an azo initiator [29]. Polymers 13b, 15, 16, and 17b were made by the addition of acryUc or propiolic acid to poly(4-vinylpyridine) and poly(N-vinylimidazole). Kinetic measurements revealed a mechanism consisting of two reactions first, addition of two molecules of acid to the polymer second, the formation of an equilibrium between the adduct and the betaine structure [30,31]. 

Statistical copolymers were reported for N-vinylimidazole and 13b [50], for acrylamide with 9a [11], 9b [12], and 9c [13], and for terpolymers of acrylamide, sodium acrylate, and 9b [51]. Several hydrolytically stable am-monioacetate and pyridiniocarboxylate monomers based on isobutylene with variable length of hydrophobic side chains did not homopolymerize, but these monomers with surfactant properties are suited for copolymerization with electron-poor monomers [52]. 

Polyzwitterions derived from polymeric heterocyclic vinyl compounds like N-vinylimidazole [54] and vinylpyridine [55, 56], containing short carboxyalkyl substituents at the quaternary nitrogen. 

A, A, and A represented the absorbancies at initial time, at completion of the reaction, and at the time of measurement, respectively, k was considered to be a pseudo first-order rate constant defined by the expression -dc/dt = k C(C/C ), where C/Cq represents the relative reactivity of the ester groups on a pol3nner chain as a function of extent of reaction. A reasonably good fit to this was obtained for reactions conducted in the absence of catalysts as well as in those catalyzed by N-methyl-imidazole and poly-(N-vinylimidazole). 

Dispersancy Incorporating dispersancy into OCP VI improvers is considerably more difficult than the case with free-radical solution chemistry, as described for PMAs. Direct copolymerization of the preferred N- or O-containing monomers is not practical since these Lewis bases will complex, and thus poison, the acidic Ziegler-Natta catalysts. The only option identified so far is to use an amount of catalyst in excess of that complexed by the polar monomer, as described for N-vinylimidazole [24] or V-vinyl succinimide [25]. 

N. PEKEL, B. SALIH, O. GUVEN, Activity studies of glucose immobilized onto ply(N-vinylimidazole and metal ion chelated Poly(N-vinylimidazole) hydrogels , J. Molecular Catalysis B Enzymatic, 21 (2003) 273-282... 

Letsinger and Klaus investigated the solvolysis of poly(acrylic acid-co-2,4-dinitro-phenyl p-vinylbenzoate) 9 catalyzed by partly protonated poly(N-vinylimidazole) 4 (57). The poly(N-vinylinudazole) showed a sufficient activity at the imidazole unit concentration much lower than that of N-methylimidazole 11 (Table 4—1), and the rate attained a limiting value at high catalyst concentrations. The rate saturation was... 

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