Shear effects on the morphology transition in a nonionic surfactant system

We report the small angle neutron scattering studies on the lamellar-to-gyroid morphology transition in a nonionic surfactant system under shear flow condition. The morphology transition is suppressed by the shear flow when the shear rate exceeds a critical value. This means that the shear field suppresses the undulation fluctuation of lamellar the structure above the critical shear rate. On the contrary when we applied shear flow in the gyroid phase, the shear-induced gyroid-to-lamellar transition was observed above the critical shear rate. The critical shear rate for the suppression of the undulation fluctuation agrees with the critical shear rate for shear induced gyroid-to-lamellar transition.