Mixed micellization and interfacial properties of alkanediyl-α, ω-bis(dimethylcetylammonium bromide) in the presence of alcohols

Mixed micellization and interfacial properties of cationic gemini surfactants alkanediyl-alpha, omega-bis(dimethylcetylammonium bromide) (16-s-16, s = 4,5,6) have been studied in the presence and absence of various alcohols (1,2-butandiol, 2-methyl-1-butanol, 2-ethyl-1-butanol, 2-butene-1,4-diol). Parameters studied include cmc (critical micelle concentration), C-20 (concentration required to reduce the surface tension of the solvent by 20 mN/m),Gamma(max) (maximum surface excess concentration at air/solution interface), and A(min) (minimum area per surfactant molecule). These parameters indicate mixed micellization between the surfactants and alcohols. The theories of Rosen and Rubingh have been used to investigate the interactions between the constituents at the interface and in the micellar solution. The micelle aggregation numbers (N-agg) of mixed systems have been obtained using the steady state fluorescence quenching technique. The micropolarity of the systems was also evaluated from the ratio of intensity of peaks (l(1)/l(3)) of the pyrene fluorescence emission spectrum. (C) 2011 Elsevier B.V. All rights reserved.