Mechanism of the enhanced spreading of some mixtures of anionic and cationic hydrocarbon chain surfactants on a highly hydrophobic polyethylene surface

Abstract

AbstractThe objective of this investigation was to measure the interfacial properties and interactions among mixtures of different cationic and anionic surfactants at the hydrophobic solid/aqueous solution interface to explain the different spreading factors or behavior of the mixed surfactants on a highly hydrophobic polyethylene (PE) film. A synergistic effect in the spreading of the mixed surfactant solutions on the PE film was observed when the surfactants were added sequentially. Other interfacial phenomena related to this surfactant spreading, such as interaction parameters at the solid/liquid (S/L) and liquid/air (L/A) interfaces in the mixtures adsorbed at various interfaces and dynamic contact angles of the mixed surfactant solutions during the process of spreading on the PE substrate, were investigated to obtain insight into this enhanced spreading. All the interaction parameters were more negative than −20, indicating very strong interaction between these cationic and anionic surfactants. The interaction parameters at the S/L interface were more negative than at the L/A interface, showing that the attractive interaction at the S/L interface was stronger than at the L/A interface. The spreading was related to the difference in the interaction parameters at the S/L and L/A interfaces and to the dynamic contact angle.