Journal of Surfactants and Detergents

, Volume 5, Issue 2, pp 151–157

The role of hydrophilic linkers


  • Edgar Acosta
    • Chemical Engineering and Materials Science Department
  • Hirotaka Uchiyama
    • Chemical Engineering and Materials Science Department
    • Civil Engineering and Environmental Science Department
  • Jeffrey H. Harwell
    • Chemical Engineering and Materials Science Department
    • College of Engineering

DOI: 10.1007/s11743-002-0215-z

Cite this article as:
Acosta, E., Uchiyama, H., Sabatini, D.A. et al. J Surfact Deterg (2002) 5: 151. doi:10.1007/s11743-002-0215-z


In microemulsion formulations, linker molecules are additives that can enhance the surfactant-oil interaction (lipophilic linkers) or the surfactant-water interaction (hydrophilic linkers). In this paper, the role of the hydrophilic linker is elucidated through solubilization studies, interfacial tension studies, and by studying the partitioning of the hydrophilic linker into an optimum middle phase. This research used alkyl naphthalene sulfonates as the hydrophilic linkers, sodium dihexyl sulfosuccinate as the surfactant, and trichloroethylene as the oil phase. The hydrophilic linkers were found to have interfacial properties between a hydrotrope and a cosurfactant. More specifically, the data show that a hydrophilic linker is an amphiphile that coadsorbs with the surfactant at the oil/water interface but that has negligible interaction with the oil phase. The role of the hydrophilic linker can thus be interpreted as opening “holes” in the interface. Based on the characteristics of alkyl naphthalene linkers, carboxylic molecules were evaluated as hydrophilic linkers. For trichloroethylene microemulsions, sodium octanoate was found to be an alternative hydrophilic linker to sodium mono- and dimethyl naphthalene sulfonates.

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© AOCS Press 2002