Volumetric, compressibility, surface tension and viscometric studies of CTAB in aqueous solutions of polymers (PEG and PVP) at different temperatures

Abstract In the present manuscript, we intend to examine the effect of neutral polymers (polyethylene glycol and polyvinyl pyrrolidone) and their blends on the post-micellization of the cationic surfactant, CTAB using conventional techniques such as density, speed of sound, surface tension and viscosity. From the parent data of density and speed of sound, we evaluated the volumetric parameters, namely apparent molar volume volumes ( ϕ v ) and adiabatic molar compressibility ( ϕ k ) along with various acoustical parameters of importance. The volumetric properties reveal different kinds of interactions that are present in the ternary system especially at lower and higher surfactant concentration without taking into consideration the post-micellar effect. Surface tension further strengthens the effect of these polymers in terms of electrostatic and hydrophobic interactions which show that surface tension decreases as the PEG content increases in the polymer mixture as compared to PVP. This may be due to the presence of residual positive charge on the PVP molecule which makes it less interactive towards the cationic surfactant. Viscosity result are further analysed in terms of relative viscosity ( η r ) and viscous relaxation time ( τ ). All these parameters form the basis of the discussion of the effect of these neutral polymers on the physical properties of CTAB. The effect of temperature has also been discussed.