Evolution of droplets of perfectly wetting liquid under the influence of thermocapillary forces

We consider the evolution of sessile droplets of a nonvolatile perfectly wetting liquid on differentially radially heated solid substrates. The heating induces thermocapillary Marangoni forces that affect the contact line dynamics. Our experiments involving a particular heating pattern reveal that the Marangoni effect suppresses the spreading of a drop, typical for perfectly wetting liquids. The result is a rather slow receding motion and a distinctive thinning of the liquid layer in the region close to the contact line. Our theoretical model, based on the lubrication approximation and incorporating the Marangoni effect, recovers the main features observed in the experiments, and in addition predicts novel features that are still to be observed.