Theory 21/Interfacial Science
Hysteresis Is a Defect Ratio
The claim
Contact angle hysteresis on a real surface is set by the ratio of defect density to droplet size rather than by the equilibrium contact angle.
01The mechanism
The contact line pins on defects; whether a defect can pin depends on how many it encounters over the droplet's perimeter, which is the ratio.
02Predictions
- P1Hysteresis should fall with droplet size.
- P2Equilibrium angle alone should mispredict.
03Refutation
Hysteresis tracking equilibrium angle would remove the defect term.