Journal of Surfactants and Detergents

, Volume 8, Issue 1, pp 3–21

Enhancing solubilization in microemulsions—State of the art and current trends

  • Jean-Louis Salager
  • Raquel E. Antón
  • David A. Sabatini
  • Jeffrey H. Harwell
  • Edgar J. Acosta
  • Laura I. Tolosa
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DOI: 10.1007/s11743-005-0328-4

Cite this article as:
Salager, J., Antón, R.E., Sabatini, D.A. et al. J Surfact Deterg (2005) 8: 3. doi:10.1007/s11743-005-0328-4

Abstract

Along a formulation scan, solubilization is maximal when a bicontinuous microemulsion is in equilibrium with both oil and water excess phases in a so-called Winsor III system. The logical way to enhance solubilization is to increase the interaction of the surfactant for both the oil and water phases, which can be easily attained by increasing the size of both the head and tail groups. However, this approach is limited by solubility constraints. Additional solubilization enhancement can be attained by introducing a molecule(s) that bridge the bulk phase and the adsorbed surfactant layer; this can be accomplished by using the so-called lipophilic and hydrophilic “linker effect” or by using block copolymer additives. In either case, the goal is to modify an extended zone in the oil and water domains close to their boundary. The intramolecular grafting of a linker group between the hydrophilic and lipophilic moieties in a surfactant results in a so-called “extended” surfactant structure, which produces enhanced solubilization, as does the surfactant/linker combination, but with the added benefit that the self-contained extended surfactant structure does not undergo selective partitioning. We conclude that an improvement in solubilization is directly related to the presence of a smooth, blurred, and expanded transition across the interfacial region from polar to apolar bulk phases.

Key Words

Extended surfactantsfuture trendsinterfacial tensionlipophilic and hydrophilic linkersmicroemulsionssolubilizationstate of the art

Abbreviations

ACN

alkane carbon number

EO

ethylene oxide

EON

ethylene oxide number

EOR

enhanced oil recovery

HLB

hydrophilic-lipophilic balance

HLD

hydrophilic-lipophilic deviation

LC

liquid crystals

OW

oil/water

S+A

surfactant+alcohol

SAD

surface affinity difference

SAOW

surfactant-alcohol-oil-water

SOW

surfactant-oil-water

WOR

water-to-oil ratio

Copyright information

© AOCS Press 2005

Authors and Affiliations

  • Jean-Louis Salager
    • 1
  • Raquel E. Antón
    • 1
  • David A. Sabatini
    • 2
  • Jeffrey H. Harwell
    • 3
  • Edgar J. Acosta
    • 3
  • Laura I. Tolosa
    • 1
  1. 1.Laboratorio de Formulación, Interfases, Reologia y Procesos (Lab. FIRP), Chemical Engineering SchoolUniversity of The AndesMéridaVenezuela
  2. 2.Civil Engineering & Environmental Science DepartmentUniversity of OklahomaNorman
  3. 3.Chemical Engineering and Material Science DepartmentUniversity of OklahomaNorman
  4. 4.Chemical Engineering and Applied Chemistry DepartmentUniversity of TorontoOntarioCanada