Wetting properties of aqueous short-chain alcohols’ solutions

Abstract

The article presents results of research on the wetting ability of aqueous solutions of short-chain alcohols in relation to selected hydrophobic materials. Polyethylene and Teflon were used as standard hydrophobic smooth materials. Dried peat with granulation d < 0.5 mm was used as the porous hydrophobic material. Physical properties of alcohols and their solutions having a direct influence on the rate of saturation of capillary layers have been discussed. The wettability of smooth surfaces was characterized by the advancing and receding contact angles and wetting tension, defined as the product of the liquid surface tension and cosine of contact angle. The contact angles were determined by Wilhelmy's method using the Krüss K-100 tensiometer. Wettability of peat was determined by measuring the mass rate of liquid imbibition by capillary forces. For comparison, analogous tests of wettability and capillary imbibition rates were carried out using sodium dodecyl sulfate solutions and solutions of typical wetting agent used in firefighting activities. The solutions of surfactants, in the range of concentrations used in extinguishing operations, showed much better wetting properties in relation to a smooth hydrophobic surface (polyethylene) than solutions of alcohols in the entire range of concentrations (up to 100%). The imbibition capacity of the hydrophobic peat layers of alcohol solutions with concentrations above 10% was higher than the solutions of surfactants. * Corresponding autor: amizerski@sgsp.edu.pl

Heterostructured Polymer‐Infiltrated Nanoparticle Films with Cavities via Capillary Rise Infiltration

“…Prior studies have shown that for water‐ethanol mixtures, the contact angle transition from non‐wetting (>90°) to partially wetting (<90°) states for some hydrophobic surfaces occurs around ethanol concentration of ≈15 vol%. [ 44,45 ] In fact, contact angle for a neat PS film at ethanol concentration of 15 vol% is smaller than 90°. [ 46,47 ] When the contact angle is greater than 90° (i.e., when the concentration of ethanol <15 vol%), the cavities stay more or less dry because the Laplace pressure (∆ P ), determined from the Young–Laplace equation (∆ P = 2 σc where c is the mean curvature of the cavity interface), is greater than 1 atm; [ 48 ] thus, the ethanol–water mixtures do not fill the cavities under ambient conditions.…”