Effect of temperature and solvent compositions on the aggregation and thermodynamic properties of the polyvinyl alcohol + tetradecyltrimethylammonium bromide mixture in aqua-organic mixed media

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 (ΔG⁰_m, ΔH⁰_m and ΔS⁰_m) 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 ($\mathrm{\Delta }{G}_m^o$) are negative for the PVA + TTAB system, suggesting a spontaneous aggregation phenomenon. The negative values of $\mathrm{\Delta }{G}_m^o$ in H₂O and 9% (w/w) mixed solvents follow the order: $\mathrm{\Delta }{G}_m^o$ (H₂O) > $\mathrm{\Delta }{G}_m^o$ (water + AN) > $\mathrm{\Delta }{G}_m^o$ (water + DO) >$\mathrm{\Delta }{G}_m^o$ (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.

GRAPHICAL ABSTRACT

KEYWORDS:

• TTAB
• PVA
• mixed solvents
• thermodynamic parameters
• hydrophobic interactions

Acknowledgements

This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding Program.

Disclosure statement

No potential conflict of interest was reported by the authors.