Note: , i.e. the fact that adhesion is thermodynamically favorable, does not guarantee that adhesion would occur. Further, whether adhesion is practical can be ascertained if we compare its magnitude to the thermal energy . If it is of the same or lower order then the Brownian motion would overcome the adhesion.
The kinetics of adhesion depends on the details of the energy curve. Even if the change in predicts adhesion, adhesion might not occur if the barrier to be overcome in bringing the two surfaces in contact is very large. only tells the change in the energy of the system in going from State 1 to State 2 (Fig. 2.2) but does not take into account the energy barrier to be overcome in going from State 1 to State 2.

Figure 2.2. Energy curve for an adhesion process