Effect of Temperature on the Dynamic Properties of Mixed Surfactant Adsorbed Layers at the Water/Hexane Interface under Low-Gravity Conditions

Abstract

<jats:p>An increase in temperature typically leads to a decrease in the interfacial tension of a water/oil interface. The addition of surfactants to the system can complicate the situation significantly, i.e., the interfacial tension can increase or decrease with an increasing temperature. For most concentrations of the two studied surfactants, the cationic tetradecyl trimethyl ammonium bromide (TTAB) and the nonionic tridecyl dimethyl phosphine oxide (C13DMPO), the measured interfacial tension of the aqueous mixed surfactant solutions against hexane increases when the temperature decreases between 30 °C and 20 °C. However, with a further temperature decrease between 20 °C and 15 °C, the reverse effect has also been observed at some concentrations, i.e., a decrease of interfacial tension. Additionally, the corresponding dilational interfacial visco-elasticity shows some discrepant temperature effects, depending on the bulk concentration and oscillation frequency. The experiments have been performed with a capillary pressure tensiometer under the conditions of micro-gravity. The reason for the positive and negative interfacial tension and visco-elasticity gradients, respectively, within certain ranges of the temperature, concentration and mixing ratios, are discussed on the basis of all available parameters, such as the solubility and partitioning of the surfactants in the two liquid phases and the oscillation frequency.</jats:p>

Influence of Surfactant Concentration on Spontaneous Emulsification Kinetics

“…Viscosities of both paraffin oil and water decrease on increasing the temperature . Temperature changes also modify the relative solubility of surfactant sand interfacial tension . Faster SE is in fact a straightforward consequence of enhanced Brownian motion of Span 80 that eases relaxation to local equilibrium and therefore naturally accelerates the overall SE kinetics.…”

“…54 Temperature changes also modify the relative solubility of surfactant sand interfacial tension. 55 Faster SE is in fact a straightforward consequence of enhanced Brownian motion of Span 80 that eases relaxation to local equilibrium and therefore naturally accelerates the overall SE kinetics. This trend is similar to the one described in the foaming ability of surfactants when the temperature is modified.…”

Anionic/nonionic surfactants for controlled synthesis of highly concentrated sub-50 nm polystyrene spheres

“… 42 When 2% concentration of styrene was used, the size decreased from 168 nm at 70 °C to 131 nm at 90 °C but at high concentrations of 8% and 10%, and the effect of the polymerization temperature became low because the high concentration of the surfactant produced small spheres even at 70 °C as shown by the results in Table 5 . Additionally, the increase in temperature would decrease the solution surface tension 43 and it would increase the solubility of the monomer, which leads to the formation of smaller size particles as discussed.…”

“…show. Additionally, the increase in temperature would decrease the solution surface tension [43] and it would increase the solubility of the monomer which leads to the formation of smaller size particles as discussed.…”

Thermodynamics, Kinetics and Dilational Visco-Elasticity of Adsorbed CnEOm Layers at the Aqueous Solution/Air Interface

“…The experiments were performed with the bubble/drop profile analysis tensiometer PAT-2 (SINTERFACE Technologies, Berlin, Germany), the principle of which was described in [12,17,18]. The temperature of the measuring cell with a volume of V = 20 mL was kept constant at 25 • C. The effect of temperature in multi-component systems can be rather complicated [36] as temperature influences not only the surface tension of the pure solvent γ 0 , but also other parameters characterising the adsorption behaviour of the surfactant, i.e., the surfactant activity coefficients, the interaction constant, the molar areas and the intrinsic compressibility. However, the variation of these parameters with temperature is outside the scope of the present study.…”