Effect of temperature and solvent compositions on the aggregation and thermodynamic properties of the polyvinyl alcohol + tetradecyltrimethylammonium bromide mixture in aqua-organic mixed media
Sharmin Sultana, Mohammad Majibur Rahman, Md. Ruhul Amin, Shahed Rana, Md. Anamul Hoque, Dileep Kumar, M. Alfakeer
Abstract
The TTAB surfactant micelle formation in presence of PVA was detected by the evaluation of CMC from the conductivity plot against the concentration of surfactant. Micellar parameters, such as critical micelle concentration (CMC), the extent of counter ion binding (β), and thermodynamic properties (ΔG0m, ΔH0m and ΔS0m) of PVA + TTAB systems have been estimated. Values of CMC of the PVA + TTAB mixed system was achieved and found to reduce with enhancing PVA concentrations which designate the survival of interactions between TTAB and PVA. The values of CMC were found to undergo an increase in the mixed solvents in comparison to the values obtained in aqueous media, which might be attributed to the reduction of the dielectric constant as well as water cohesive energy. The values of free energy of micellisation (ΔGmo) are negative for the PVA + TTAB system, suggesting a spontaneous aggregation phenomenon. The negative values of ΔGmo in H2O and 9% (w/w) mixed solvents follow the order: ΔGmo (H2O) > ΔGmo (water + AN) > ΔGmo (water + DO) >ΔGmo (water + DMF). The thermodynamic properties of transfer were also estimated for the move of PVA+ TTAB mixed system from water to aqua-organic mixture of solvents.