Recently, it has been shown that small changes, such as different position of the substituent on an aromatic ring in the structure [1,2] and the hydrophobicity of counterions [3] considerably influence the self-assembly process like micellization of ionic surfactants.
This effect has been investigated on cationic surfactant dodecyltrimethylammonium chloride and relatively small number of counterions (pharmaceutically important anion mainly). The problem is that there are no much appropriate anions which differ in the hydrophobicity and can be chosen for further investigation. Therefore ionic liquids can serve excellent model systems because they exist in diverse structure and the hydrophobic part of the cation can be varied broadly.
In this work the influence of imidazolium based ionic liquids on aggregation processes of anionic surfactant sodium dodecylsufate will be studied by isothermal titration calorimetry giving the data on the thermodynamic parameters of aggregation process (free energy, enthalpy, entropy and heat capacity changes). The relation between the heat capacity change and the hydrophobic effect, affected by the additional hydrophobic surface (from counterion) included into the dehydration process upon micellization, will be discussed.
References:
1. Šarac B.; Cerkovnik, J.; Ancian, B.; Mériguet, G. ; Roger, G. ; Durand-Vidal, S.; Bešter-Rogač, M. Colloid Polym.Sci., 2011, 289, 1597-1607.
2. Šarac, B.; Mériguet, G.; Ancian, B., Bešter-Rogač, M. Langmuir, 2013, 29, 4460-4469.
3. Kroflič, A.; Šarac, B.; Cerkovnik, J.; Bešter-Rogač, M. Colloid Surface A, in press.
marija.bester@fkkt.uni-lj.si
