Influence of n-alcohols on aqueous DTAB micelles studied by ultrasonic analysis

Abstract

Abstract The influence of chain length of n-alcohols such as 1-butanol, 1-pentanol, 1-hexanol and 1-heptanol on cationic dodecyl trimethyl ammonium bromide (DTAB) micelles has been investigated. The effect of concentration was determined at alcohol concentrations of (10, 20, 30, 40 and 50) mM and at temperatures of 298.15 K, 303.15 K, 308.15 K and 313.15 K using ultrasonic velocity, density, viscosity and conductivity measurements. To study molecular interactions in micelles of various mixtures of DTAB and n-alcohols by using acoustical parameters, such as adiabatic compres-sibility (β ad), intermicellar free length (L f ), acoustic impedance (Z), molar volume (V M ) have been calculated by using ultrasonic velocity (U) and density (ρ). With the help of the trends observed when varying these parameters, the molecular interactions and thus the micellar growth of mixed systems of DTAB and n–alcohol were discussed. Viscosity data such as absolute viscosity, viscous relaxation time, oil solubilization, foam stability and conductance data complemented the observed ultrasonic data.