К статистической теории растворов в критическом растворителестатья
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Дата последнего поиска статьи во внешних источниках: 29 мая 2015 г.
Аннотация:The thermodynamics of high polymers in equilibrium with a low-molecular solvent with a large correlation radius (super-and near-critical solvent) is studied. Special attention is devoted to the analysis of typical phase diagrams describing the conditions of solubility of a polymer in such a solvent. The nature of these diagrams is determined by the existence of long-range multiparticle attraction between the monomers, which increases as the critical point of the solvent is approached. At the critical point the contribution of this attraction to the free energy of the system is nonanalytic with respect to the polymer concentration. It is shown that the nontrivial dependences of the polymer-polymer and polymer-solvent coupling constants, which appear in the phenomenological analysis, on the pressure and temperature of the solvent play an important role in the quantitative analysis of the phase diagrams of the solubility of the polymer. These dependences are found in explicit form under the assumption that in the absence of intermonomer bonds the system can be described as a compressible two-component lattice alloy. The partition function of the system under study is represented as a functional integral over two coupled, strongly fluctuating fields, one of which, describing the fluctuations of the polymer density, is the 0 component. By virtue of the specific nature of the problem, the effective temperature corresponding to the 0-component of the field cannot be specified independently, but can be determined by minimizing the total free energy of the system.