Effect of the conditions of synthesis on the structure of hydrophobically modified polyacrylamides and rheology of their solutions and gelsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Местоположение издательства:Road Town, United Kingdom
Первая страница:385
Последняя страница:394
Аннотация:Using the method of micellar copolymerization, hydrophobically modified copolymers of various types and compositions are synthesized. They are binary and ternary copolymers of acrylamide containing small amounts (0.2-3 mol %) of acrylamide or methacrylate derivatives with apolar side groups (9 or 12 CH2 groups) and, in the case of ternary copolymers, also containing monomers capable of ionization (mostly sodium acrylate). The properties of the amide and ester copolymers are found to differ. The relationship between the composition, structure, and formation conditions of the hydrophobically modified copolymers, on the one hand, and the formation and rheological properties of their physical gels, on the other hand, is studied. The zero Newtonian viscosity and the elastic modulus of the gels are shown to be determined by the hydrophobicity of the copolymer. The latter property depends both on the length or amount of hydrophobic groups in the macromolecules and on the arrangement of these groups along the chain. The properties of the gels show an extreme dependence on the amount of charged groups in the copolymer due to the mutual influence of charges and hydrophobic groups. As the number of charges in the chain increases, it becomes possible to introduce a larger amount of hydrophobic groups into the copolymer without phase separation of its get. This and other factors make it possible to vary the rheological properties of gels of hydrophobically modified copolymers and their stability with respect to elevated temperatures within wide limits.