Molecular aspects of the main phase transition in lipid systems as a weak first-order phase transition: 1. Model of thermodynamic behavior of lipid membranes

摘要

The possibility to describe the principal phase transition in lipid systems as a weak orientational first-order phase transition with characteristics close to those of a second-order phase transition characterized by pretransition phenomena and rather strong fluctuations has been considered. A first order transition is explained by interactions between fluctuations of molecule orientations and density fluctuations at a low shear modulus. The jumpwise behavior of enthalpy, volume, heat capacity, compressibility, sound velocity and absorption, and the order parameter are analyzed. It is shown that because of molecular van der Waals interactions the shear modulus should give rise to more pronounced jumps of the above quantities with an increase in molecule lengths. (c) 2005 Pleiades Publishing, Inc.