Surface force experiments have been carried out to investigate the dynamics of adhesion for grafted polymer-coated glass spheres in a solvent. The quality of solvent has been varied both by changing the relative concentrations in a mixed solvent system and by variations in temperature in order to investigate the effect on the measured adhesion. Under very poor solvent conditions (far from theta conditions) there is a contact time dependence of the magnitude of the adhesion, that can be explained in terms of polymer interpenetration. This interpenetration is consistent with the diffusion following primitive path fluctuation dynamics. An increase in the maximum applied load leads to a decrease in adhesion which is attributed to a slower diffusion rate due to squeezing out of the solvent from the contact zone. Under slightly poor solvent conditions (near-theta conditions), any polymer interdiffusion is found to be rapid on the experimental time frame. In this case the adhesion is strongly dependent on the separation rate, which is interpreted in terms of viscoclastic losses at the crack tip.