Dilational visco-elasticity of BLG adsorption layers at the solution/tetradecane interface - Effect of pH and ionic strength

Drop profile analysis tensiometry is applied to measure the dilational visco-elasticity of BLG at the buffered aqueous solution/tetradecane (W/TD) interface using oscillating drops of TD immersed in W at frequencies between 0.01-0.2 Hz. The buffered solutions were investigated at pH 3, pH 5 (isoelectric point) and pH 7 at different buffer concentrations (1 mM, 10 mM and 100 mM). The real part of the complex visco-elasticity shows a maximum when plotted as a function of the interfacial pressure Pi. In contrast to the water/air surface (W/A) where we observe maximum elasticity values between 15 and 20 mN/m, at the W/TD interface these maximum values are up to 65-70 mM/m, which is in parallel with the much higher interfacial pressure values at the W/TD interface when compared to the W/A surface. (C) 2016 Elsevier B.V. All rights reserved.