Equilibrium solutions in the mechanical theory of fluid microstructures

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A mechanical-molecular theory for fluid microstructures is outlined. It is assumed that average molecular densities and forces vary continuously across the fluid microstructure in accordance with the mechanical principles of conservation of mass and momentum. To account for the large density gradients, and therefore for the long-range molecular interactions, it is also assumed that the molecular forces can be represented in terms of the gradients of the molecular densities. In contrast to previous theories of fluid microstructures, which are seriously restricted by the use of classical thermodynamic structure within the spinodal region, the mechanical theory is free of thermodynamics. We confine attention to equilibrium, and prove that the differential equation governing a one-dimensional fluid microstructure has only three types of solutions possible: transitions, reversals, and oscillations. Physically, they correspond to liquid-vapor interfaces, thin films, and layered structures. © 1983.

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Journal of Colloid And Interface Science