OVER THE HORIZON SANS - MEASUREMENTS ON NEAR-SURFACE POISEUILLE SHEAR-INDUCED ORDERING OF DILUTE-SOLUTIONS OF THREAD-LIKE MICELLES

Although the behavior of a fluid under shear near a surface can be exp ected to be critically important to its drag and lubrication propertie s, most shear measurements to date have been of the bulk. This paper o utlines the use of a specially developed Poiseuille shear cell at graz ing incidence to measure the small-angle neutron scattering (SANS) sig nal from the first few tens of microns in the interfacial region. We i llustrate the technique with measurements made on the near-surface ord ering in flow past a quartz surface of dilute surfactant solutions com prising highly extended self-assembling ''thread-like'' micelles.