On a general method to determine van der Waals interactions in inhomogeneous thin film

This work mostly deals with the van der Waals interactions and some basic on stability of thin films having evaporation. We have started from the first principles of electromagnetism that is Maxwell’s equation to derive the relation for the van der Waals interaction energy. Using this method, we have found out the interaction energy for three media case with constant dielectic permeability, three media case with exponential variation of dielectric permeability in the middle layer and constant dielectic permeability in the outer layers, three media case with linear variation of dielectric permeability in the middle layer and constant dielectic permeability in the outer layers, four layer case with constant dielectric permeabilities for all layers. This work is also applicable in polymers where there is a gradual variation in dielectric properties. We also have done a linear stability analysis for a thin film having evaporation and surfactant on the surface. We have used the lubriaction theory and linear stability analysis for finding out the growth rate of disturbance and how the stability is affected by the surfactant concentration, thermal gradiant and rate of evaporatio