The e
ffect o
f sur
factants鈥?type and concentration on the inter
facial
tension and contact angle in the presence o
f hydrophilic silica particles was investigated. Silica particles have been shown to have an antagonistic e
ffect on inter
facial
tension and contact angle in the presence o
f both W/O and O/W sur
factants. Silica particles, combined with W/O sur
factant, have no e
ffect on inter
facial
tension, which is only dictated by the sur
factant concentration, while they strongly a
ffect inter
facial
tension when combined with O/W sur
factants. At low O/W sur
factant, both particles and sur
factant are adsorbed at the inter
face, modi
fying the inter
face structure. At higher concentration, inter
facial
tension is only dictated by the sur
factant.
By increasing the surfactant concentration, the contact angle that a drop of aqueous phase assumes on a glass substrate placed in oil media decreases or increases depending on whether the surfactant is of W/O or O/W type, respectively. This is due to the modification of the wettability of the glass by the oil or water induced by the surfactants. Regardless of the surfactant鈥檚 type, the contact angle profile was dictated by both particles and surfactant at low surfactant concentration, whereas it is dictated by the surfactant only at high concentration.