Temperature- and Pressure-dependences of Shape Fluctuations in a Ternary Microemulsion System

Abstract

Shape fluctuations in a microemulsion system composed of Aerosol-OT (AOT), D₂O and deuterated decane were investigated by means of neutron spin echo. In this system, a water-in-oil droplet structure at ambient temperature and pressure decomposes into two-phases, both with increasing temperature and pressure. However, its dynamical behavior was different. The observed effective diffusion constant of the droplet shape fluctuation increased with increasing temperature, while it decreased with increasing pressure. Temperature- and pressure-dependences of a bending modulus of AOT monolayers were estimated, and it was confirmed that AOT monolayers become floppy with increasing temperature and stiff with increasing pressure.