Depletion interaction measured by colloidal probe atomic force microscopy

We investigated the depletion interaction between stearylated silica surfaces in cyclohexane in the presence of dissolved polydimethylsiloxane by means of colloidal probe atomic force microscopy. We found that the range of the depletion interaction decreases with increasing concentration. Furthermore the depletion interaction in this system is much weaker than predicted by theories assuming a hard-wall type interaction between polymer segments and surface. We conclude that the interaction between the polymer segments and the surface is not zero, which weakens the depletion interaction