Ionogenic monomers

In one of these groups the polymer network consisting of synthetic and natural polymers is formed directly in the process of grafting. The degree of swelling is determined by the reaction condititions including the component ratio, initiation method, and ionogenic monomer content. 

Many ionogenic monomers containing a polymerizable carbon double bond have been reported in the literature, and therefore a wide variety of anionic, cationic, and amphophilic polyelectrolytes may be synthesized using free radical polymerizations. Examples of anionic ionogenic monomers which have been used to synthesize anionic polyelectrolytes include acrylic acid [4-10], methac-rylic acid [6-8,11,12], sodium styrenesulfonate [7,13,14], p-styrene carboxylic... 

Chemical groups capable of ionic binding of heparin may be introduced onto the polymer surface by radiation grafting of ionogenic monomers, e.g., 2- or 4-vinyl-pyridine, dimethylaminoethyl methacrylate, etc. 64,65). Heparinization proceeds as shown below ... 

As can be seen from the last column of Table II, DSC studies did not indicate any change in the glass transition temperature of the polyacrylates due to the presence and/or concentration of the ionogenic monomer (SST) incorporated. We have observed the same behavior in styrene, methyl acrylate and other systems (26). Other workers have also reported similar results in ionomers synthesized by the direct reactions of various acrylic acid salts and covalent vinyl monomers (27). This indicates either the simultaneous homopolymerization of both monomers or a "block copolymerization. 

A historical perspective on the development of hydrophobe-modified, water-soluble polymers is presented. The various synthetic procedures used to obtain different associative thickeners are discussed in terms of the complexities in ionogenic monomer polymerizations. This discussion serves two purposes. The first is to present the peculiarities in anionic and cationic polymer synthesis in contiguity with previous work on water-soluble polymers that related only to their use. The second purpose is to draw parallels between the discontinuities in the classical chain-growth polymerization of nonionic with ionogenic monomers and those that should be expected to occur with hydrophobe-modified monomers, but for which there are insufficient data in associative thickener technology to define properly. 

These parameters also have been useful through the Alfrey-Price Q e scheme (33) for assessing the merit of new monomers in multicomponent macromolecular compositions. From the data just cited for ionogenic monomers and from the strength of associations that affect significant viscosity increases cited in Chapters 18 and 21-27 for hydrophobic monomers, it... 

The reactivity of the neutralized, strong-acid monomers [e.g., sodium styrenesulfonate (32) and 2-sulfoethyl methacrylate (30)] with nonionic monomers also is dependent on the changes in polarity of the system (i.e., dielectric constant, solvation, and hydration) and with solution pH (Table IV for the sodium styrenesulfonate studies). The effect also is evident (39) in the copolymerization of two ionogenic monomers, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, with different pK values. For acrylic acid, the reactivity ratio is 0.740 0.13 at pH 7 and 1.58 0.15 at pH 2-4. For 2-acrylamido-2-methylpropanesulfonic acid, the reactivity ratio was 0.187 0.09 at pH 7 and 0.111 0.03 at pH 2-4. These studies (39)... 

The copolymerization of hydrophobically modified monomers should exhibit similar behavior, but opposite in direction to ionogenic monomers. Increasing hydrophobe size and solubility diflPerences with the nonionic monomer should make it difficult to obtain significant spacings between hydro-phobic monomers in chain-growth copolymerizations. In view of what has been delineated in surfactant-micelle (40) and ionogenic monomer behaviors, a multitude of unique structural possibilities could be obtained in hydrophobically modified copolymers synthesized by free-radical chain-growth processes. 

Besides acrylic and methacrylic acids, the following are commercially available ionogenic monomers ... 

Up to now, exeept for ICI, the industry did not apply too much polymerizable surfactants. Some people prefer to use ionogenic monomers such as acrylic, itaconic, or methacrylic acid, as well as styrene sulfonate or related compounds. Anyway, interest in polymerizable surfactants seems to be growing, and a few patents have recently been published [134]. 

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