Surface and thermodynamic study of micellization of non ionic surfactant/diblock copolymer system as revealed by surface tension and conductivity

Surface physico-chemical and thermodynamic properties of non ionic surfactants (Tween 20 and Tween 80) with diblock copolymer poly (oxyethylene/oxybutylene) (E39B19) at 298 K have been investigated by surface tension and conductivity techniques. The surface tensiometery were used to study the critical micelle concentration (CMC), surface excess concentration (Г), minimum area per molecule (A), free energy of micellization (∆Gm) and free energy of adsorption (∆Gads). From the observed surface properties it was concluded that the process of micellization is spontaneous and exothermic. Conductometry technique was used to determine critical micelle concentration (CMC), degree of ionization (α), degree of counter ion binding (β). The addition of diblock copolymer to the surfactant solutions increase the values of degree of ionization (α), degree of counter ion binding (β). Although it led to decrease in the values of CMC indicating that the process of micellization is more favorable and spontaneous. Received 20 Nov 2016, Revised 10 Jan 2017, Accepted 15 Jan 2017