DETERMINATION OF THE STRUCTURE OF A SURFACTANT LAYER ADSORBED AT THE SILICA WATER INTERFACE BY NEUTRON REFLECTION

Neutron reflection from the solid/liquid interface has been used to determine the structure of an adsorbed layer of hexaoxyethylene glycol monododecyl ether (C12E6) on quartz. Contrast variation experiments show that C12E6 adsorbs as a bilayer, the ethylene oxide chains forming the layers adjacent to the quartz and the bulk solution. The thickness of the hydrocarbon core of the layer was found to be 17±3 Å and the area per molecule 23 ± 3 Å2. The ethylene oxide chain regions were 16±3 Å thick. The average hydration number of a single ethylene oxide group was found to be 2.0±0.5. © 1989