Energitics of micellizaion of sodium n-dodecyl sulfate at physiological conditions using isothermal titration calorimetry

Article

Abstract

The micellization characteristics of sodium n-dodecyl sulfate (SDS) have been investigated by microcalorimetric technique at conditions close to the physiological ones. The thermodynamics of micellization were studied at 20, 25, 30, 35 and 40 °C in 50 mM HEPES buffer, pH 7.4 and 160 mM NaCl using isothermal titration calorimetric (ITC) technique. The calorimeter can operate in a stepwise addition mode, providing an excellent method of determination of critical micelle concentration (CMC) and enthalpy of demicellization (and hence micellization). It can as well distinguish between aggregating and non-aggregating amphiphiles (solutes) in solution. The dilution enthalpy (∆H dil) was calculated and graphed versus concentration in order to determine the micellization enthalpy (∆H mic) and CMC. In addition to the CMC and ∆H mic, the effective micellar charge fraction (α) of the ionic surfactant micellization process can also be determined from ITC curves. The Gibbs free energy of the micellization (∆G mic), entropy of the micellization (∆S mic), and specific heat capacity of the micellization (∆C P,mic) process have been evaluated by the direct calorimetric method (mass-action model) as well as by the indirect method of van’t Hoff by processing the CMC and α results of microcalorimetry at different temperatures. The differences of the results obtained by these two procedures have been discussed. The presence of NaCl (160 mM) in the solutions decreased the CMC of SDS. The enthalpy changes associated with micelle dissociation were temperature-dependent, indicating the importance of hydrophobic interactions. The ∆G mic was found to be negative, implying, as expected, that micellization occurs spontaneously once the CMC has been reached. The values of ∆G mic were found to become more negative with increasing temperature and the ∆S mic was found to decrease with increasing temperature in both models.

Keywords

Critical micelle concentration Isothermal titration calorimetry Micellization thermodynamics Sodium n-dodecyl sulfate van’t Hoff enthalpy 

Notes

Acknowledgements

The financial supports of this work by the Research Council of Isfahan University are gratefully acknowledged (grant number 861129).

References

  1. 1.
    Clint JH. Surfactant aggregation. New York: Chapman and Hall; 1991.Google Scholar
  2. 2.
    Moulik SP. Micelles: self-organized surfactants assemblies. Curr Sci. 1996;71:368–76.Google Scholar
  3. 3.
    Emerson MF, Holtzer A. Hydrophobic bond in micellar systems: effects of various additives on the stability of micelles of sodium dodecyl sulfate and of n-dodecyltrimethyl ammonium bromide. J Phys Chem. 1967;71:3320–30.CrossRefGoogle Scholar
  4. 4.
    Tanford C. The hydrophobic effect: formation of micelles and biological membranes. New York: Wiley; 1980.Google Scholar
  5. 5.
    Moroi A. Micelles: theoretical and applied aspects. New York: Plenum Press; 1992.Google Scholar
  6. 6.
    Kumar S, David SL, Din K. Effects of various hydrocarbons on micellar growth. J Am Oil Chem Soc. 1997;74:797–801.CrossRefGoogle Scholar
  7. 7.
    Sugioka H, Matsuoka K, Moroi Y. Temperature effect on formation of sodium cholate micelles. J Colloid Interface Sci. 2003;259:156–62.CrossRefGoogle Scholar
  8. 8.
    Esposito C, Colicchio P, Facchiano A, Ragone R. Effect of a weak electrolyte on the critical micellar concentration of sodium dodecyl sulfate. J Colloid Interface Sci. 1998;200:310–2.CrossRefGoogle Scholar
  9. 9.
    Ghosh S. Surface chemical and micellar properties of binary and ternary surfactant mixtures (cetylpyridinium chloride, tween-40, and brij-56) in an aqueous medium. J Colloid Interface Sci. 2001;244:128–38.CrossRefGoogle Scholar
  10. 10.
    Ghosh S, Moulik SP. Interfacial and micellization behaviors of binary and ternary mixtures of amphiphiles (tween-20, brij-35, and sodium dodecyl sulfate) in aqueous medium. J Colloid Interface Sci. 1998;208:357–66.CrossRefGoogle Scholar
  11. 11.
    McBain JW. Mobility of highly-charged micelles. Trans Faraday Soc. 1913;9:99–101.Google Scholar
  12. 12.
    Kresheck GC, Hargraves WA. Thermometric titration studies of the effect of head group, chain length, solvent, and temperature on the thermodynamics of micelle formation. J Colloid Interface Sci. 1974;48:481–93.CrossRefGoogle Scholar
  13. 13.
    Mukherjee K, Mukherjee DC, Moulik SP. Thermodynamics of micellization of aerosol OT in binary mixtures of water, formamide, ethylene glycol, and dioxane. J Phys Chem. 1994;98:4713–8.CrossRefGoogle Scholar
  14. 14.
    Jana PK, Moulik SP. Interaction of bile salts with hexadecyltrimethyl ammonium bromide and sodium dodecyl sulfate. J Phys Chem. 1991;95:9525–32.CrossRefGoogle Scholar
  15. 15.
    Haque MdE, Das AR, Moulik SP. Behaviors of sodium deoxycholate (NaDC) and polyoxyethylene tert-octylphenyl ether (triton x-100) at the air/water interface and in the bulk. J Phys Chem. 1995;99:14032–8.CrossRefGoogle Scholar
  16. 16.
    Bordbar AK, Hosseinzadeh R, Norozi MH. Interaction of a homologous series of n-alkyl trimethyl ammonium bromides with eggwhite lysozyme. J Therm Anal Cal. 2007;87:453–6.CrossRefGoogle Scholar
  17. 17.
    Majhi PR, Moulik SP. Energetics of micellization: reassessment by a high-sensitivity titration microcalorimeter. Langmuir. 1998;14:3986–90.CrossRefGoogle Scholar
  18. 18.
    Chatterjee A, Maiti S, Sanyal SK, Moulik SP. Micellization and related behaviors of n-cetyl-n-ethanolyl-n,n-dimethyl and n-cetyl-n,n-diethanolyl-n-methyl ammonium bromide. Langmuir. 2002;18:2998–3004.CrossRefGoogle Scholar
  19. 19.
    Razafindralambo H, Dufour S, Paquot M, Deleu M. Thermodynamic studies of the binding interactions of surfactin analogues to lipid vesicles. J Therm Anal Cal. 2009;95:817–21.CrossRefGoogle Scholar
  20. 20.
    Mazer NA, Olofsson G. Calorimetric studies of micelle formation and micellar growth in sodium dodecyl sulfate solutions. J Phys Chem. 1982;86:4584–93.CrossRefGoogle Scholar
  21. 21.
    Gu G, Yan H, Chen W, Wang W. Observation of micelle formation and micellar structural transition from sphere to rod by microcalorimetry. J Colloid Interface Sci. 1996;178:614–9.CrossRefGoogle Scholar
  22. 22.
    Chen D, Zhu JX, Yuan P, Yang SJ, Chen T-H, He HP. Preparation and characterization of anion-cation surfactants modified montmorillonite. J Therm Anal Cal. 2008;94:841–8.CrossRefGoogle Scholar
  23. 23.
    Leharne SA. Calorimetric analysis of vesicular systems. J Therm Anal Cal. 2002;69:465–85.CrossRefGoogle Scholar
  24. 24.
    Lagergel S, Kamyshny A, Magdassi S, Partyka S. Calorimetric methods applied to the investigation of divided systems in colloid science. J Therm Anal Cal. 2003;71:291–310.CrossRefGoogle Scholar
  25. 25.
    Dai S, Tam KC. Isothermal titration calorimetric studies on the temperature dependence of binding interactions between poly(propylene glycol)s and sodium dodecyl sulfate. Langmuir. 2004;20:2177–83.CrossRefGoogle Scholar
  26. 26.
    Stodghill SP, Smith AE, O’Haver JH. Thermodynamics of micellization and adsorption of three alkyltrimethyl ammonium bromides using isothermal titration calorimetry. Langmuir. 2004;20:11387–92.CrossRefGoogle Scholar
  27. 27.
    Thongngam M, McClements DJ. Influence of pH, ionic strength, and temperature on self-association and interactions of sodium dodecyl sulfate in the absence and presence of chitosan. Langmuir. 2005;21:79–86.CrossRefGoogle Scholar
  28. 28.
    Paula S, Sus W, Tuchtenhagen J, Blume A. Thermodynamics of micelle formation as a function of temperature: a high sensitivity titration calorimetry study. J Phys Chem. 1995;99:11742–51.CrossRefGoogle Scholar
  29. 29.
    Johnson I, Olofsson G, Jonsson B. Micelle formation of ionic amphiphiles. Thermochemical test of a thermodyanamic model. J Chem Soc Faraday Trans. 1987;83:3331–44.CrossRefGoogle Scholar
  30. 30.
    Bergstrom S, Olofsson G. A calorimetric study of three long-chain ionic surfactants. Thermochim Acta. 1986;109:155–64.CrossRefGoogle Scholar
  31. 31.
    Bandopadhyay A, Moulik SP. Counterion binding behavior of micelles of sodium dodecyl sulphate and bile salts in the pure state, in mutually mixed states and mixed with a nonionic surfactant. Colloid Polym Sci. 1988;266:455–61.CrossRefGoogle Scholar
  32. 32.
    Blandamer MJ, Cullis PM, Pure JBFN. Calorimetric studies of macromolecular aqueous solutions. Pure Appl Chem. 1996;68:1577–82.CrossRefGoogle Scholar
  33. 33.
    Bijma K, Engberts J, Blandamer MJ, Cullis PM, Last PM, Irlam KD, et al. Classification of calorimetric titration plots for alkyltrimethyl ammonium and alkylpyridinium cationic surfactants in aqueous solutions. J Chem Soc Faraday Trans. 1997;93:1579–84.CrossRefGoogle Scholar
  34. 34.
    Stenius P, Backlund S, Ekwall P. Thermodynamic and transport properties of organic salts. IUPAC Chem Data Ser. 1980;28:295.Google Scholar
  35. 35.
    Hait SK, Moulik SP, Palepu R. Refined method of assessment of parameters of micellization of surfactants and percolation of w/o microemulsions. Langmuir. 2002;18:2471–6.CrossRefGoogle Scholar
  36. 36.
    Dai S, Tam KC. Isothermal titration calorimetric studies of alkyl phenol ethoxylate surfactants in aqueous solutions. Colloids Surf A: Physicochem Eng Aspects. 2003;229:157–68.CrossRefGoogle Scholar
  37. 37.
    McClements DJ. Isothermal titration calorimetry study of pectin-ionic surfactant interactions. J Agric Food Chem. 2000;48:5604–11.CrossRefGoogle Scholar
  38. 38.
    Olofsson G, Wang G. Polymer-surfactant systems: isothermal titration and temperature scanning calorimetric studies of polymer-surfactant systems. New York: Marcel Dekker; 1998.Google Scholar
  39. 39.
    Ananthapadmanabhan KP. Interactions of surfactants with polymers and proteins: surfactants solutions, adsorption and aggregation properties. London: CRC Press; 1993.Google Scholar
  40. 40.
    Thongngam M, McClements DJ. Characterization of interactions between chitosan and an anionic surfactant. J Agric Food Chem. 2004;52:987–91.CrossRefGoogle Scholar
  41. 41.
    Wangsakarn A, Chinachoti P, McClements DJ. Maltodextrin-anionic surfactant interactions: isothermal titration calorimetry and surface tension study. J Agric Food Chem. 2001;49:5039–45.CrossRefGoogle Scholar
  42. 42.
    Jonsson B, Lindman B, Holmberg K, Kronberg B. Surfactant and polymers in aqueous solution. New York: Wiley; 1998.Google Scholar
  43. 43.
    Fuguet E, Rafols C, Bosch E, Roses M. Characterization of the solvation properties of sodium n-dodecyl sulfate micelles in buffered and unbuffered aqueous phases by solvatochromic indicators. Langmuir. 2003;19:55–62.CrossRefGoogle Scholar
  44. 44.
    Mukerjee P. The nature of the association equilibria and hydrophobic bonding in aqueous solutions of association colloids. Adv Colloid Interface Sci. 1967;1:242–75.CrossRefGoogle Scholar
  45. 45.
    Attwood D, Florence AT. Surfactant systems: their chemistry, pharmacy and biology. New York: Chapman and Hall; 1983.Google Scholar
  46. 46.
    Wang Y, Han B, Yan H, Kwak JCT. Microcalorimetry study of interaction between ionic surfactants and hydrophobically modified polymers in aqueous solutions. Langmuir. 1997;13:3119–23.CrossRefGoogle Scholar
  47. 47.
    Chatterjee A, Moulik SP, Sanyal SK, Mishra BK, Puri PM. Thermodynamics of micelle formation of ionic surfactants: a critical assessment for sodium dodecyl sulfate, cetylpyridinium chloride and dioctyl sulfosuccinate (Na salt) by microcalorimetric, conductometric, and tensiometric measurements. J Phys Chem B. 2001;105:12823–31.CrossRefGoogle Scholar
  48. 48.
    Rosen MJ. Surfactants and interfacial phenomena. New York: Wiley; 1989.Google Scholar
  49. 49.
    Evans DF, Wennerstrom H. The colloidal domain where physics, chemistry, biology and technology meet. New York: Wiley; 1999.Google Scholar
  50. 50.
    Kresheck GC. Comparison of the calorimetric and van’t Hoff enthalpy of micelle formation for a nonionic surfactant in H2O and D2O solutions from 15 to 40 °C. J Phys Chem B. 1998;102:6596–600.CrossRefGoogle Scholar
  51. 51.
    Franks F, Reid DS. Water: a comprehensive treatise. New York: Plenum Press; 1975.Google Scholar
  52. 52.
    Naghibi H, Tamura A, Sturtevant JM. Significant discrepancies between van’t Hoff and calorimetric enthalpies. Proc Natl Acad Sci USA. 1995;92:5597–99.CrossRefGoogle Scholar
  53. 53.
    Onori G, Santucci A. Calorimetric study of the micellization of n-butoxyethanol in water. J Phys Chem B. 1997;101:4662–6.CrossRefGoogle Scholar
  54. 54.
    Blume A, Tuchtenhagen J, Paula S. Application of titration calorimetry to study binding of ions, detergents, and polypeptides to lipid bilayers. Prog Colloid Polym Sci. 1993;93:118–22.CrossRefGoogle Scholar
  55. 55.
    Goddard ED, Benson GC. Conductivity of aqueous solutions of some paraffin chain salts. Can J Chem. 1957;35:986–91.CrossRefGoogle Scholar

Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2009

Authors and Affiliations

  1. 1.Laboratory of Biophysical Chemistry, Department of ChemistryUniversity of IsfahanIsfahanIslamic Republic of Iran

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