Ion Exchange functional groups

Monomer and polymer electrolytes containing ion-exchangeable functional groups, (I), and an ionic Uquid functional group, (II), were prepared by Best et al. (1) and used in fuel cells. 

Ion exchanger Functional group Capacity toward U (mg/g) X10- (cmVg) Reference... 

Ion-exchange chromatography is a very predictable technique because the mechanism is well defined. The capacity factor (k) for the binding of an ionic solute to an ion-exchange functional group in lEC is directly related to the concentration (c) of salt in the mobile phase ... 

Explanations to abbreviations derived from trivial terms for ion exchange functional groups (1) Sulfo-, sulfomethyl-, sulfoethyl-, sulfopropyl-, sulfobutyl- (2) Phosphonic- (3) Carboxyl-, carboxy-methyl- (4) Trimethylaminomethyl-, Triethylaminoethyl- (5) Hydroxyethyidimethylaminomethyl- ... 

The term homogeneous is used loosely to describe membranes that are not classified as heterogeneous. On a molecular scale no membrane is truly homogeneous, because the unlike parts of the polymer, hydrophihc ion-exchange functional groups and hydrophobic hydrocarbon chains, tend to become segregated into clusters that are much smaller than the dimensions of the resin particles in the heterogeneous membranes. 

Typical homogeneous membranes have a polymer matrix of styrene cross-linked with divinylbenzene (DVB) and ion-exchange functional groups of sulfonic acid or quaternary amines. Manufacture of DVB yields an impure product containing nearly 50% of ethylstyrene, which participates in the polymerization but does not accept functional groups readily. In some cases the film of styrene-DVB copolymer is made in one step, and the functional groups are added in subsequent steps. 

Ion-permeable membranes are also made by swelling existing films with styrene and DVB, which can then be post-treated to add functional groups, or by grafting of ion-exchange functional groups directly onto the polymer matrix of existing films. For example, free radicals formed by radiation of polyethylene or fluoropolymer films become sites for addition of vinyl sulfonic acid, acrylic acid or vinyl amines [30]. 

Simultaneous analysis of alkali and alkaline earth metals can only be performed with weak acid cation exchangers, using carboxylic groups as ion-exchange functionality group and usually with methanesulfonic acid as the eluent. 

Ion-exchange functional groups are chemically bonded to the support, often through a polymeric layer which totally... 

Variations in the chemical nature of the ion-exchange functional group have a major effect on selectivity in IC. This is particularly true for anion exchangers. Some of these variations in functional group structure were discussed in Chapter 3. 

More than 5 years ago, two type IV mixed-mode columns that are based on an alkyl chain with terminal ion-exchange functional groups were commercialized under the trade name Acclaim Mixed-Mode WAX-1 [67] and Acclaim... 

The four Acclaim Mixed-Mode columns mentioned in Section 6.7.2 - Acclaim Mixed-Mode WAX-1, Acclaim Mixed-Mode WCX-1, Acclaim Trinity PI, and Acclaim Trinity P2 - can also be used under HILIC conditions. Acclaim Mixed-Mode WAX-1 and Acclaim Mixed-Mode WCX-1 are based on an alkyl chain with terminal ion-exchange functional groups. Because of this column chemistry, both columns offer multiple retention mechanisms, including ion exchange, reversed phase, and HILIC. As an example. Figure 7.7 demonstrates that in highly organic mobile phase. Acclaim Mixed-Mode WCX-1 can serve as a HILIC column. Hydrophilic analytes such as cytosine elute later than naphthalene as a hydrophobic neutral analyte. 

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