Polymethacrylic acid gels

WM Anspach, JA Marinsky. Complexing of nickel(II) and cobalt(II) by a polymethacrylic acid gel and its linear poly electrolyte analog. J Phys Chem 79 433-439, 1975. 

The humates present in soil are polyelectrolytes and bear some similarity to polyacrylic acid and polymethacrylic acid (49, 50). The molecular weight distribution for the humates is considerable fulvic acid fractions of 1,000 daltons have been isolated (51) while humic acid molecular weights obtained by gel chromatography are in the range 17,000 to 100,000 daltons according to the type of soil from which it was extracted (52). However, ultracentrifugation analysis indicates a molecular range of 2,000 to 1,500,000 daltons for humic acids (55). 

An electrochemical method projected for the determination of the effective volume of a colloidally dispersed polyelec-trolyte phase in aqueous media was evaluated. Experiments with the highly flexible Sephadex (carboxymethyldextran) gel and the more rigidly cross-linked polymethacrylic acid resin were performed for this purpose. With the well-defined resin (gel) phase it was possible to measure the polymer volume as a function of every experimental condition used to test fully the fundamental concepts on which the method is based. The results substantiate the validity of concepts developed. Application of this method for estimating the effective volume of weakly acidic (basic) polymers in solution seems worthy of further consideration. However, some modification of the treatment of the electrochemical data is necessary for polymeric sols, and this aspect is discussed briefly. 

It is notable that at high pH the gel starts to collapse once more. This is due to charge screening by the Na ion involved in adjusting the pH inducing further coiling. At low pH, the polymethacrylic acid (PMAA) chains form highly compact hydrophobic clusters, which are joined by short extended polymer chains. As the pH is increased the size of the clusters decreases up to a limit,... 

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. 

Stationary phases containing carboxylic acid functional groups are now frequently used for I EC instead of strong-acid sulfonated resins. The carboxylic acid particles are often a polymethacrylate gel. These materials have found extensive use for the analysis of low concentrations of both cations and anions in acid rain. Acid rain caused by SO2 and NOx in air is a major environmental pollution problem in many parts of the world. The major cationic components of acid rain are Na, NH4, K, Mg and Ca, and the major anionic components are cr, NOg and SO4 . The ionic balance between the total positive charge and negative charge of... 

In 1971, Davankov et al. achieved the first baseline separation of enantiomers using a small molecule-based CSP consisting of L-proline [1], Since then, a wide range of chiral small compounds, which include amino acids, cyclodextrins, macrocyclic glycopeptides, cinchona alkaloids, crown ethers, jt-basic or rt-acidic aromatic compounds, etc., have been used as CSPs [2—6], On the other hand, the polymer-based CSPs are further divided into two categories, i.e., synthetic and natural chiral polymers [7, 8]. Typical examples of the synthetic polymers are molecularly imprinted polymer gels, poly(meth)acrylamides, polymethacrylates, polymaleimides, and polyamides, and those of the natural polymers include polysaccharide derivatives and proteins. 

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