Nonionic amphiphilic bilayer structures under shear

The effect of shear on the lamellar phase of amphiphilic systems has been widely studied in a variety of amphiphilic systems as a function of shear rate. In this investigation, we fixed the shear rate and performed temperature scan experiments on a two-component (C10E3-water) system. We observed a sequence of phases, from the low to high temperature range: multilamellar vesicle to planar lamellar to sponge phase. The shear-induced multilamellar vesicle (MLV) phase exhibited the most interesting behavior and is the main focus of the present study. Small-angle neutron and light scattering techniques were used to elucidate the microstructure, to determine the bilayer orientation, and to characterize the size of these structures. The interlamellar spacing was observed to be the same in the lamellar as in the MLV phase, and the MLV phase exhibited symmetrical scattering in the neutral and flow directions, indicating that the layers in the besides are spherically shaped at the selected shear rate ((gamma) over dot 100 s-(1)). With all the information that we could gather for the planar lamellar and MLV phases, we used the framework of the elastic curvature energy model to describe qualitatively the stability of these bilayer structures formed at a given shear rate.