Nonionic amphiphilic bilayer structures under shear

The effect of shear on the lamellar phase of amphiphilic systems has been w idely studied in a variety of amphiphilic systems as a function of shear ra te. In this investigation, we fixed the shear rate and performed temperatur e scan experiments on a two-component (C10E3-water) system. We observed a s equence of phases, from the low to high temperature range: multilamellar ve sicle to planar lamellar to sponge phase. The shear-induced multilamellar v esicle (MLV) phase exhibited the most interesting behavior and is the main focus of the present study. Small-angle neutron and light scattering techni ques were used to elucidate the microstructure, to determine the bilayer or ientation, and to characterize the size of these structures. The interlamel lar 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 flo w directions, indicating that the layers in the besides are spherically sha ped at the selected shear rate ((gamma) over dot 100 s-(1)). With all the i nformation that we could gather for the planar lamellar and MLV phases, we used the framework of the elastic curvature energy model to describe qualit atively the stability of these bilayer structures formed at a given shear r ate.