VINYL IMIDAZOLE COPOLYMER

A fluid loss additive useful in cementing oil and gas wells is a blend [423,424,1015] of a copolymer of acrylamide/vinyl imidazole. The second component in the blend is a copolymer of vinylpyrrolidone and the sodium salt of vinyl sulfonate. Details are given in Table 2-2. The copolymers are mixed together in the range of 20 80 to 80 20. Sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate can be used as a dispersant. 

Table 4—3. Amides from l-acyl-4-vinyl imidazole/divinylbenzene copolymer.

In this case, a moderately water-soluble amphiphilic N-vinylcaprolaclam (NVC1) played the role of a fl-unit, and a well-water-compatible N-vinyl-imidazole (NVIAz) served as a P-unil. The polymerization was carried out in a medium of 10% aqueous dimethylsulfoxide (DMSO). The addition of DMSO to the reaction solvent was necessary because of insufficient NVC1 solubility in pure water. It was also shown that in this solvent mixture, the NVCl-homopolymers and NVCl/NVIAz-copolymers retained their LCST-behaviour [26,28]. Hence, the DMSO in the reaction solvent did not significantly suppress the hydrophobic interactions of the NVC1 units. The polymerization was initiated by the redox system (N,N,N, N -tetramethylethylenediamine (TMEDA) + ammonium persulphate (APS)) and was carried out at 65 °C (1st step). This condition was very important, since admittedly the temperature was higher than the phase separation threshold of the reaction bulk when the polymeric products were formed that is, under these thermal conditions, hydrophobically-induced folding as the NVCl-blocks appear was ensured. After completion of the reaction, the... 

Experimentally, the described synthetic strategy was first realized by Lozinsky et al. [80,81], who studied the redox-initiated free-radical copolymerization of thermosensitive N-vinylcaprolac lam with hydrophilic N-vinyl-imidazole at different temperatures. These and other experimental studies [82 - 84] showed the universality of this approach of obtaining copolymers capable of forming nanostructures with a core-shell morphology. 

The hydrolysis of copolymers containing vinyl imidazole (Vim) as the third component, poly(MAOT-co-AA-co-VIm) (No. 15), poly(AOT-co-AA-co-VIm) (No. 13), and poly(MAOA-co-AA-co-VIm) (No. 17), is shown in Fig. 3. These copoly-... 

Heme (7 a) with a triblock copolymer containing styrene and 1-vinyl imidazole is teversiUy, slowly oxidized. ... 

Copol3rmers of 1-alkyl-4- or 5-vinyliiiiidazole and 4(5)-vinyl-imidazole (I) were synthesized with variations in the alkyl chain length and the 4(5)-vinylimidazole content.(10) The incorporation of alkylated imidazole residues into the backbone of poly[4(5)-vinylimidazole] not only provided efficient regeneration of the catalysts, but also imparted water solubility to the copolymers. (11) These copolymers were compared with mixtures of their component homopolymers having the same vinylimidazole content. 

Effect of Variations in Alkyl Chain Length on Copolymers of Vinyl imidazoles... 

A water-soluble block copolymer composed of hydrophilic poly(ethylene oxide) and hydrophobic poly(styrene-co-vinyl-imidazole) was synthesized (3). Cu ion was complexed with the imidazole residue of the central hydrophobic residue. The com-plexation of about one Cu ion per block copolymer molecule resulted in a pale-blue aqueous and homogeneous solution. 

Dispersancy Solution copolymers are comparatively easy to produce in dispersant form as copolymerization with an appropriate polar monomer is relatively straightforward. If the polar monomer is also a methacrylate, reactivity ratios are essentially the same and no special procedures are required to produce random copolymers. Commercial examples have included dimethyl (or diethyl)aminoethyl methacrylate [11], hydroxyethyl methacrylate [12] and dimethylamino-ethyl methacrylamide [13]. 2-Methyl-5-vinyl pyridine [14] has also been used commercially, reactivity ratios are such that it copolymerizes slightly faster than alkyl methacrylates. Although composition drift is not severe, it should be added in a programmed fashion if a uniform distribution is desired. V-vinyl pyrrolidinone, in contrast, copolymerizes very sluggishly with methacrylates and is best incorporated via a graft reaction [15], sometimes also grafted in combination with V-vinyl imidazole [16]. Since solution chemistry is used to produce dispersant polymethacrylates, like preparation of the base polymer, only relatively simple process modifications are necessary to produce dispersants commercially. 

As discussed before, the borderline between polysoaps and polyelectrolytes or thickeners is determined by the hydrophilic-hydrophobic balance HLB, as well as by the length and the density of the hydrophobic tails chosen. The longer they are, the lower is the content of hydrophobic tails - the Critical Alkyl Group Content CAC [52, 75] - needed in order to produce polysoap behaviour (cf. Sect. 2.3.2). For poly(2-vinylpyridine) and poly(4-vinylpyridine), about 20% of derivatization with octyl tails and about 10% of derivatization with dodecyl tails are needed as a minimum to obtain the characteristic low viscosities [49, 52, 75, 133, 141, 317] (Fig. 17). Comparable CAC values are obtained for derivatized poly(vinyl-imidazol)s [140] and for poly(allylamine)s [152]. Similarly in anionic copolymers of poly(sodium 2-acrylamido-2-... 

Kunitake, T. Okahata, Y. Multifunctional hydrolytic catalyses. 7. Cooperative catalysis of the hydrolysis of phenyl esters by a copolymer of iV-methacryloyl hydroxamic acid and 4-vinyl imidazole. J. Am. Chem. Soc. 1976, 98, 7793-7799. 

The thermooxidative degradation and SiOx film formation of poly(vinyl imidazole-co-vinyl trimethoxysilane) on copper was investigated. Thermal degradation of the copolymer was catalysed by copper in the film and at the substrate surface. Copper in the copolymer film contributed to the formation of a copper-containing SiOx film during thermal degradation. Copper oxides in the film interacted with the SiOx film to form a copper-rich phase near the film defects and cracks (142). 

Copolymer of vinyl imidazole (VI) and vinyl trimethoxy silane (VTS)... 

Copolymer of vinyl imidazole and vinyl trimethoxy silane films on Cu IRRAS, SEM Effect of copolymer composition on Cn corrosion protection at 360°C in air 1129... 

Structural studies of polymer surfaces. Materials that have been studied include PMMA [239], PMMA-polypyrrole composites [240], polyfchloromethyl styrene) honnd 1,4,8,11-tetrazacyclotetradecane, polyfchloromethyl styrene) honnd thenoyl triflnoroacetone [241], poly(dimethyl siloxane)-polyamide copolymers [242], PS [243], ion-implanted PE [244], monoazido-terminated polyethylene oxide [245], polynrethanes [246], polyaniline [247], flnorinated polymer films [248], poly(o-tolnidine) [249], polyetherimide and poly benzimidazole [250], polyfnllerene palladinm [251], imidazole-containing imidazolylethyl maleamic acid-octadecyl vinyl ether copolymer [252], polyphenylene vinylene ether [253], thiophene oligomers [254], flnorinated styrene-isoprene derivative of a methyl methacrylate-hydroxyethyl methacrylate copolymer [255], polythiophene [256], dibromoalkane-hexaflnorisopropylidene diphenol and bisphenol A [257], and geopolymers [258]. 

Rranco, T. T., Galaev, I. Y, Hatti-Kaul, R., Holmberg, N., Bu, L., Mattiasson, B. (1997). Aqueous two-phase system formed by thermoreactive vinyl imidazole/vinyl caprolactam copolymer and dextran for partitioning of a protein with a poly histidine tail. Biotechnology Techniques, II, 231-236. 

Apart from EO and PO, pNIPAM, PVCL and copolymers of A-isopropylacrylamide and JV-vinyl caprolactam with vinyl imidazole were tested (Persson et al, 2000). The copolymers with imidazole units change their properties with pH, becoming positively charged at lower pH levels and uncharged at levels above pH 7.0. This provides the possibility of directing the protein partitioning by changing the pH in the system rather than the more common addition of a salt (Persson et a/., 2000). 

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