Using neutron reflectometry and reflection geometry “near-surface” SANS to investigate surfactant micelle organization at a solid-solution interface

We have used simultaneous neutron reflectometry (NR) and reflection geometry “near-surface” small angle neutron scattering (NS-SANS) to investigate the ordering of cetyltrimethylammonium bromide (CTAB) micelles in aqueous (D2O) solution in the proximity of a quartz surface as a function of concentration and temperature. The NR measurements allow us to determine coherent micellar organization within a few thousand angstroms of the interface while NS-SANS allows simultaneous monitoring of “bulk” states to the greater depth of grazing incidence penetration into the solution, typically 10-100 μm. We illustrate the utility of this monitoring using the example of an apparent Poiseuille surface shear-induced change in micellar organization which is more probably the result of slight temperature increase.