In reflectometry a laser beam is reflected off the surface The kinetics of adsorption of nano-sized silica particles on a resulting in a certain intensity of parallel and perpendicular polymer pretreated surface were followed in situ by using optical polarized light. Changes in the refractive index close to the reflectometry in a stagnation point flow setup. Conversion of the surface due to polymer or particle adsorption give rise to a reflectometric signal to the surface coverage could be performed change in the ratio of these intensities. To interpret the meausing a homogeneous slab model which was verified by determinsured change in intensity ratio upon adsorption a model is ing the particle density on SEM pictures taken in the stagnation needed. For polymers or very small particles a model can point and by comparison with a model which includes the particube used in which the adsorbed layer is treated as a homogelate nature of the layer explicitly. The effects of salt concentration
neous slab with a certain refractive index. For larger particles on the plateau adsorbed amounts for all particle sizes can be described with an effective hard sphere concept. Although initial the particulate nature of the layer has to be taken into acslopes and plateau values are in reasonable agreement with a rancount, which can be done by using the formalism described dom sequential adsorption model, this model does not accurately in Refs. (13-15). We will compare results obtained for the describe the evolution of the surface coverage as a function of time largest particles used in this study to both the homogeneous in a stagnation point flow system. ᭧ 1998 Academic Press model and the particle approach. In a more sophisticated Key Words: particle adsorption; stagnation point flow; reflecreflectometry setup scanning angle experiments can be pertometry; particle size; salt concentration; effective hard sphere formed, which can give additional information, e.g., on the model.
particle size (13)(14)(15).
We choose to test the suitability of optical reflectometry in stagnation point flow to study the adsorption of nano-