Interfacial rheological behavior of ionic liquid-type imidazolium surfactant

The interface tension and interface dilational properties of a series of ionic liquid-type imidazolium surfactants solutions, [Cnmim]Br, at the decane–water interface are reported. The dilational rheology properties are measured by means of oscillating drop method. The influences of dilational frequency, bulk concentration and structure on dilational rheology properties have been investigated. The results reveal that the interface dilational elasticity of the imidazolium surfactants with longer hydrophobic chain is larger than that with shorter hydrophobic chain at lower concentration, but the opposite is observed at high [Cnmim]Br surfactants solution concentrations. At lower concentrations, with the length of hydrophobic chain increasing, the dilational modulus increase resulting from the greater hydrophobic interaction. However, at higher concentration, [Cnmim]Br surfactants with longer hydrophobic chain desorbs from the interface more easily, but more difficult to resist the interface deformation.