Comparative study of transformation of micellar structures exhibited by CTAB and TTAB in binary systems by positron lifetime spectroscopy

摘要

The cationic surfactants of general formula RN(CH3)3 X, where R is an Alkyl chain and X is an anion, have interesting properties. They are among the most widely used bacteriocides, wetting and antistatic agents. The physiochemical properties of these surfactants are largely determined by the nature of counter ion and alkyl chain length. The micellar structures of cetyl tri methyl ammonium bromide (CTAB) and its other homologue have been investigated employing several conventional techniques. However, due to relative insensitive and perturbation introduced by the probe, in some of the techniques, the molecular level information in these systems is rather scarce. Similarly detailed structures of the aggregates in so called single phase regions are far from being completely understood. In order to get better information about the micellar structures and understanding of their systematic, positron has also been employed as a non -destructive probe for the comparative studies of transformations of micellar structures exhibited by CTAB and TTAB in aqueous and non aqueous binary systems. The system was investigated in wide range of surfactant concentrations by positron lifetime spectroscopy. Results obtained in these investigations are discussed in this paper.