Abstract
Small-angle neutron scattering (SANS) and neutron spin echo (NSE) spectroscopy have been used to elucidate static and dynamic structures of a microemulsion system composed of a nonionic surfactant, water, and oil. Using the contrast variation neutron scattering technique, static structure parameters are evaluated, and the molecular volume change with pressure is calculated. The bending elastic modulus increases with increasing pressure. This tendency is similar to the microemulsion system composed of anionic surfactant, water, and oil. Therefore, a universal feature of the surfactant membrane as a response to pressure is clarified, that is, the surfactant membrane becomes rigid at high pressure due to the increase of density of the hydrophobic tail of surfactant molecules and their aggregates.
