EFFECTS OF SURFACE FLUCTUATIONS IN A 2-DIMENSIONAL EMULSION

We investigate the role of geometrical shape fluctuations for the ther modynamic properties of a polydisperse ensemble of two-dimensional dro plets. The energy of a droplet derives from the Hamiltonian for surfac e bending rigidity with spontaneous curvature. Interactions between in dividual droplets are omitted, but polydispersity in droplet size and arbitrarily large distortions of the droplet shape are incorporated fu lly. The physical property of self-avoidance is approximated by the le ss stringent topological requirement of unit winding number. This topo logical model shows that some physical observables are considerably mo re sensitive to the presence of shape fluctuations than others. The sp ecific heat, in particular, is strongly affected by the presence of sh ape fluctuations. This observable is also very sensitive to approximat e treatments of the shape fluctuations. The periodic Gaussian or Villa in approximation is found to be reliable at all temperatures, whereas the Gaussian approximation fails except for very low temperatures. (C) 1998 Elsevier Science B.V. All rights reserved.