Studies on the mixed micelles of alkyltrimethylammonium bromides and butanediyl-1,4-bis(alkyldimethylammonium bromide) dimeric surfactants in the presence and absence of ethylene glycol at different temperatures.

Mixed micellization of two cationic dimeric surfactants butanediyl-1,4-bis(alkyldimethylammonium bromide) [C(m)H(2m+1)N(+)(CH(3))(2)-(CH(2))(4)-N(+)(CH(3))(2)C(m)H(2m+1),2Br(-)] with their monomeric counterparts alkyltrimethylammonium bromides [C(m)H(2m+1)N(+)(CH(3))(3)Br(-)](m=14 and 16) has been studied at different temperatures (298.15-323.15K) in presence and absence of ethylene glycol (EG) using conductivity data. Steady state fluorescence quenching (SSFQ) measurements were performed to estimate the average aggregation number (N(agg)) of the mixed micelles at 298.15K. The ideal cmc values, experimental and ideal micellar compositions, interaction parameters, activity coefficients of the components, etc. have been evaluated by considering theoretical models of Clint, Rubingh and Rodenas. The analysis reveals that the fraction of the monomeric surfactant in the mixed micelles is higher than the expected ideal micellar mole fraction, and in most of the cases mixed micelles of the studied components become more ideal in the presence of EG.