THE APPLICATION OF LATERAL FORCE MICROSCOPY TO PARTICLE REMOVAL IN AQUEOUS POLYMER-SOLUTIONS

An atomic force microscope (AFM) has been used to examine the effect o f a typical polymeric dispersant on the adhesion between an iron oxide sphere and a silicon wafer in the presence and absence of shear. Two separate methods for the determination of the lateral spring constant (k(1)) of AFM cantilevers were employed. Determination of k(1) allows the absolute, rather than relative, shear force to be extracted from t he lateral force output of the AFM. A comparison is made between the p ull-off force (no shear) and the lateral force as the dispersant conce ntration and loading force are varied. While in both cases the magnitu de of the forces decrease with increasing dispersant concentration, th e effect is much less marked for the lateral force. A linear increase in removal forces with increasing loading force was observed. For a gi ven load, the removal force is typically an order of magnitude smaller in the presence of shear.