Interaction study of mixed micellar system of isoquinoline based surface active ionic liquids and cationic surfactant in aqueous medium

Abstract

Surface-active ionic liquids (SAILs) can modify the physiological properties of conventional surfactants. Mixed micelles of isoquinoline-based SAILs, dodecylisoquinolinium bromide [C12iQuin][Br], tetradecylisoquinolinium bromide [C14iQuin][Br] and cationic surfactant, dodecyltrimethylammonium bromide (DTAB) in aqueous medium and their interactions have been studied by employing conductometry and 1H NMR technique. The critical micelle concentration (cmc) and various thermodynamic parameters have been calculated from conductometry measurements. Mixed micellar parameters such as ideal cmc (cmc*), micellar mole fraction ( $$ {X}_1^m $$ ), micellar interaction parameter (βm) and activity coefficients (f1) and (f2) of component 1 (SAIL) and component 2 (DTAB) have been evaluated by applying Clint, Rubingh and Motomura theoretical models. The interaction between SAILs and surfactant has been found synergistic and non-ideal. The peak merging and broadening of protons suggests the growth of micelles. Use of SAILs as an additive effectively reduce the cmc that is indicated by negative value of interaction parameter (βm).