Assessment of cationic amphiphile-biopolymer interactions: Effects of organic compounds and temperature on association phenomena

Abstract

The present study reveals the micellization nature of cetyltrimethylammonium bromide (CTAB) in aqueous solutions of sodium alginate (SA) with short-chain alcohols (containing 1–3 carbon number) and glycerol using the conductometric method at temperatures from 305.55 to 325.55 K with 5 K interval. The aggregation property has been characterized by assessing critical micelle concentration (CMC) from conductivity (κ) versus surfactant concentration plots. The micellar variables such as CMC and the extent of counterion binding (β) demonstrate the dependency on the variation in solvent categories, composition of the solvent mixture, and working temperatures. For the CTAB + SA (0.01 %, w/w) mixed system at 310.55 K, the increased CMC values were acquired with increasing quantity of alcohols and glycerol introduced. The CMC values showed a rising trend with the escalation of working temperature. The negative Gibbs free energy ${(\Delta G}_m^0)$ values were attained for the CTAB + SA system in all investigating solvents, which stated the spontaneous occurrence of aggregation of the employed system. In aqueous alcohols media, the enthalpy changes (${∆H}_m^o$) were attained as positive and negative at lower and elevated investigated temperatures respectively; while in aqueous glycerol environment, the ${∆H}_m^o$ values were acquired to be all negative at inspected temperatures. The entropy changes (${∆S}_m^o$) were realized to be positive for the investigated cases. The compensation temperature (T_c) values have been achieved to be in the series of 241.91 K to 318.75 K which showed a good analogy to the literature stated data for the micellization of amphiphiles. The attained knowledge from the present investigation might help in improving the formulations in industries including pharmaceuticals, foods, and cosmetics.