Imidazolium-functionalized polymers

The imidazolium salt functionalized polymer 12 also functions as an iodide sensor, rapidly changing color in the presence of sodium iodide (Ho and Leclerc 2003). Iodide-mediated aggregation was highly sensitive to the length of the side chain coimecting the imidazolium salt to the polythiophene backbone. A variety of... 

Several successful strategies are available in the literature [14] that increase the thermal stability of organic molecules. Full utilization of these strategies for the preparation of surface treatments of layered silicates with enhanced thermal stability for the development of polymer-clay nanocomposites has yet to be realized. An example of an effective strategy is the utilization of quaternary ammonium and phosphonium functional polystyrene as a surface treatment for montmorillonite that is employed to prepare polymer-clay nanocomposites [15]. TGA indicated a significant increase in the thermal stability of the organoclay and the polymer-clay nanocomposite. Imidazolium functional surface modifier for montmorillonite demonstrated a significant increase in the thermal stability of ABS terpolymer-clay nanocomposite when compared to the pure polymer and polymer-clay nanocomposites where the surface modification of the montmorillonite was produced with traditional quats [16]. These experiments were via TGA measurements. 

Li X, Ni X, Liang Z, Shen Z (2012) Preparation of main-chain imidazolium-functionalized amphiphilic block copolymers through combination of condensation polymerization and nitroxide-mediated free radical polymerization and their micelle study. J Polym Sci A Polym Chem 50 2037-2044... 

Hossain, M. A. Lim, Y Lee, S. Jang, H. Choi, S. Hong, T. Jin, L. Kim, W. G., Synthesis and characterization of tetra-imidazolium hydroxides poly(fluorenylene ether sulfone) anion exchange membranes. Reactive and Functional Polymers 2013, 73(9), 1299-1305. 

In an extension of the work to chiral chemistry 244), the imidazolium cation of the ionic liquid was modified to carry a chiral substituent. The high cost of the chiral cation could be justified as the chiral ionic liquid, [MBMIM ] , can be reused. In the ATRP of soluble methyl acrylate, a small effect of the chiral ionic liquid on the polymer tacticity was observed. The use of a chiral ionic liquid as a solvent could lead to applications in other areas of catalysis. The synthesis of imidazolium-containing ionic liquids functionalized with chiral natural amino acids has already been reported 245), as have less expensive chiral ionic liquids(2- (5). 

In particular, highly stable Pd nanoparticles, protected by an imidazolium based ionic polymer in a functionalized IL, can be easily prepared. These Pd nanoparticles are excellent pre-catalysts for Suzuki, Heck and Stille coupling reactions and can be stored without undergoing degradation for at least two years. 

To show their suitability as replacements for conventional imidazolium-based ionic liquids the authors demonstrated that these protic ionic liquids performed well as solvents for the Heck reaction. The alcohol functionality also has the benefit that it can be used to tether substrates, allowing these ionic liquids to be used as recyclable homogenous supports, an alternative to traditional polymer resins [61]. 

Relative oxygen permeability of nanocomposites with imidazolium modified montmorillonite as a function of filler volume fraction. The permeation behavior is compared with composites containing dioctadecyldimethylammo-nium ions [22] ( ) Ammonium and (a) Imidazolium composites. The dotted lines only serve as guides. (Reproduced from Mittal, V., Eur. Polym. /., 43, 3727, 2007. With permission from Elsevier.)... 

The binding behavior of methyl orange to severed homopolymers and copolymers containing imidazole and imidazolium salts was investigated as a function of polymer structure and counterion. The polymers were fractionated and characterized by light scattering, viscosity, and turbidimetry. Dye binding was measured by equilibrium dialysis, spectrophotometric titration, and microcalorimetry. 

Figure 8.16 Plausible mechanism over carboxyl-functionalized imidazolium-based IL grafted onto cross-linked divinylbenzene polymer (adapted from Ref [61]).

Gel and solid polymer electrolytes aim to combine the function of the electrolyte and separator into a single component to reduce the number of parts in an ES and increase the potential window through the higher stability offered by a polymer matrix. A gel electrolyte incorporates a liquid electrolyte into a microporous polymer matrix that holds in the liquid electrolyte through capillary forces, creating a solid polymer film. The chosen separator must be insoluble in the desired electrolyte and provide adequate ionic conductivity. Non-polar rigid polymers such as PTFE, PVA, PVdF, and cellulose acetate offer good ion conductivity when used as gel electrolytes [114]. Based on the data in Table 4.9, the ionic conductivity of EtMeIm+Bp4 is 14 mS.cm". Ionic conductivity of the same imidazolium salt used as a gel electrolyte in a PVdF matrix retains 5 mS.cm [115]. 

Several organic compounds, especially imidazolium, pyridinium, and phosphonium salts, were shown to have noticeably higher thermal stability, and they could be applied as compatibilizers for polymer/clay nanocomposites, providing a good level of dispersion and improved properties. Additional functionalization of surfactants is most often aimed at improvement of miscibility or synergistic enhancement of nanocomposite properties however, any change in the chemical constitution of an organomodifier involves simultaneous alteration of its thermal characteristic. 

Sun et al. reported the use of pwlymer supported hydroxyl-functionalized IL catalyst for the PC synthesis [51]. They prep>ared hydroxyethyl imidazolium-based IL immobilized on PS (PS-[HEIm]Br), and the corresponding im-functionalized immobilized IL (PS-[EIm]Br) for comparison (Scheme 15). An excellent PC yield of 98% was obtained with PS-[HEIm]Br at 120°C and CO2 pressure of 2.5 MPa for 4 h, while that with PS-[EIm]Br was a lower value of 64%. Thus, introducing the OH group is effective for the CO2 cycloaddition reaction even for the polymer immobilized IL system. 

Tris (2,4,6-trimethoxyphenyl) benzyl phosphonium hydroxide shows the highest basicity ever reported. Its HEM has the highest specific hydroxide conductivity among all reported cationic functional group-based HEMs, typically about twice that of trimethyl benzyl ammonium and more than foiu- times that of methyl imidazolium (39 [5], 19 [31], and 8.4mSgcm mmor [32] respectively, with the same polysulfone polymer matrix and homogeneous membrane structure in each case) (Table 6.2). 

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