Effect of mixed micellization on dimensions of 1-butyl-3-methylimidazolium dodecylsulfate micelles in presence of electrolytes

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2015-11, Vol.484, p.498-507
• Main Authors: Chat, Oyais Ahmad, Maswal, Masrat, Hassan, P.A., Aswal, V.K., Rather, G.M., Dar, Aijaz Ahmad
• Format: Article
• Language: English
• Subjects: [bmim][DS]; Brij30; DLS; Mixed micelles; SANS
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2015.08.032

[Display omitted] We report microstructural evolution of [bmim][DS]+Brij30 mixed micelles in presence of Na+ and NH4+. •Salt effect on microstructural changes in [bmim][DS] in presence of Brij30 is presented.•Size of [bmim][DS] micelles increases with addition of non-ionic Brij30.•NH4+ is more potent in increasing micellar size than Na+ as per Hofmeister series.•Temperature caused decrease in size of [bmim][DS]+Brij30 mixed micelles.•SANS reveals Brij30 favors sphere to rod transition and salts increase rod length. The association behavior of an amphiphilic ionic liquid 1-butyl-3-methylimidazolium dodecylsulfate ([bmim][DS]) and a non-ionic surfactant Brij30, in the presence and absence of NH4Cl and NaCl, was investigated using DLS, SANS and Rheology. The apparent hydrodynamic radius (Rh) of the mixed micelles increases with increase in mole fraction of the non-ionic component. The variation in micellar size with Brij30 mole fraction is sensitive to the nature and concentration of the two salts. The increase in size of mixed micelles is more pronounced in presence of NH4Cl than NaCl, owing to higher salting out effect of NH4+ ions compared to Na+ ions. The hydrodynamic radius of the mixed mcielles decreases with increase in temperature from 25°C to 45°C, due to dehydration of oxyethylene units in Brij30. SANS studies reveal that [bmim][DS] micelles grow significantly with increase in Brij30 mole fraction and the presence of salt facilitates micellar elongation. The zero shear viscosity of mixed micelles in the presence of 0.4M NH4Cl and NaCl increases with Brij30 mole fraction, the effect being more in presence of the former.