(303d) Can Dynamic Contact Angle be Measured Using Molecular Modeling?

Many natural phenomena, such as, rolling of water droplet on lotus leaf, dryness of bird feather even after immersing in water and skimming of water strider on water surface, have inspired humans to prepare man-made superhydrophobic and self cleaning surfaces. These modified surfaces have potential applications in variety of areas ranging from chemical industry to food appliances. In the design of such surfaces, the key parameter is their wetting behaviour which is characterized by equilibrium and dynamic (advancing and receding) contact angles. Molecular modeling has a potential to provide detail information of contact angle phenomena down to a sub-nanometer length scale resolution, which is essential for success of these materials. 

We have proposed a method for determining the dynamic contact angle at the three-phase contact between a
solid, a liquid, and a vapor under an applied force, using molecular simulation. The method is
demonstrated using a Lennard-Jones (LJ) fluid in contact with a cylindrical shell of the FCC Lennard-Jones
solid. We report the advancing and receding contact angles and the contact angle hysteresis for LJ system using this approach. We also evaluate the increase in force required to wet fully an array of solid cylinders (robustness) with decrease in separation distance between cylinders. The dynamic contact angle is
characterized by partial slipping of the three phase contact line when a force is applied.