Nanoscale surface patterns were observed in thin films of mexylaminotriazine-functionalized glasses containing polar groups upon the application of an electric field at temperatures over their glass transition temperatures (T-g). This phenomenon occurred due to the surface deformation process initiated by external electric field instabilities on the films. The minimal surface deformation temperature (T-dewet) relative to T-g was found to increase as a function of the polarity of the substituents and the surface pattern roughness was observed to increase linearly with temperature for a fixed electric field and exposure time. Reversal of the electrical field polarity and the use of both hydrophilic and hydrophobic substrates did not significantly change the surface deformation behavior of the films, which is due to the deposition of charges at the free interface. The application of a mask between the electric field electrodes allowed to selectively pattern areas that are exposed. Furthermore, it was observed that this surface deformation behavior was reversible, since heating the films to a temperature above T-g in the absence of an electric field caused the erasure of all surface patterns.