A new method for evaluating the most stable contact angle using tilting plate experiments

We propose to measure the most accurate contact angle for calculation of solid surface tensions from the most mechanically stable drop. From tilting plate experiments, we probed the sliding behavior of sessile drops with equal volume but different contact angle. We measured two critical tilt angles for each drop. When the surface was tilted beyond the first critical inclination, the drop began to slide down at the uphill or downhill point of its contact line. The second critical tilt angle occurred with the global motion of the sliding drop. We were able to identify the most stable drop when the first critical tilt angle was maximum, and it was then when both critical tilt angles agreed. We validated this methodology with the most stable contact angle values of polymer surfaces evaluated using mechanical vibrations.