Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants
1
Institut Charles Gerhardt, UMR-5253 CNRS-UM-ENSCM, Place Eugène Bataillon, F-34095 Montpellier cedex 5, France
2
Department of Chemistry, University Badji-Mokhtar, BP12 Annaba, Algeria
3
Laboratoire Charles Coulomb, UMR 5221 CNRS-UM, Place Eugène Bataillon, F-34095 Montpellier cedex 5, France
*
Authors to whom correspondence should be addressed.
Int. J. Mol. Sci. 2016, 17(2), 223; https://doi.org/10.3390/ijms17020223
Received: 22 December 2015 / Revised: 1 February 2016 / Accepted: 1 February 2016 / Published: 6 February 2016
(This article belongs to the Special Issue Ionic Liquids 2016 and Selected Papers from ILMAT III)
Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH°) were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group.
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Keywords:
alkylguanidinium chlorides; surfactants; Krafft temperature; surface tension; critical micelle concentration; standard enthalpy of micelle formation
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MDPI and ACS Style
Bouchal, R.; Hamel, A.; Hesemann, P.; In, M.; Prelot, B.; Zajac, J. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants. Int. J. Mol. Sci. 2016, 17, 223. https://doi.org/10.3390/ijms17020223
AMA Style
Bouchal R, Hamel A, Hesemann P, In M, Prelot B, Zajac J. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants. International Journal of Molecular Sciences. 2016; 17(2):223. https://doi.org/10.3390/ijms17020223
Chicago/Turabian StyleBouchal, Roza; Hamel, Abdellah; Hesemann, Peter; In, Martin; Prelot, Bénédicte; Zajac, Jerzy. 2016. "Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants" Int. J. Mol. Sci. 17, no. 2: 223. https://doi.org/10.3390/ijms17020223
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