A method of decreasing a water contact angle and/or increasing a surface energy of a liquid is disclosed herein, the method comprising exposing the liquid to a plasma treatment. Further disclosed is a plasma-treated liquid exhibiting a decreased water contact angle and/or increased surface energy, compared to the water contact angle and/or surface energy, respectively, of a non-treated corresponding liquid. Methods for combining a first liquid and a second liquid, or for enhancing an adhesion between a liquid and a surface of another substance, the methods comprising exposing a liquid to plasma treatment, are further disclose herein, as well as a method of predicting an apparent contact angle of a liquid droplet on a surface of a substance.