Fluorinated ionic surfactant microemulsions in hydrofluorocarbon 134a (HFC 134a)

Patel, N. ORCID: https://orcid.org/0000-0002-8600-0663, Marlow, M. and Lawrence, M. J. (2003) Fluorinated ionic surfactant microemulsions in hydrofluorocarbon 134a (HFC 134a). Journal of Colloid and Interface Science, 258 (2). pp. 354-362. ISSN 0021-9797 doi: 10.1016/S0021-9797(02)00071-1

Abstract/Summary

The factors influencing the formation of water-in-134a-propellant microemulsions using the fluorinated ionic surfactants ammonium perfluorooctanoate, ammonium perfluoroheptanoate, and sodium perfluorooctanoate has been determined. None of the fluorinated ionic surfactants could be used to prepare clear, one-phase systems when used as sole surfactant, but they could be when combined with a short-chain fluoro- or hydrocarbon alcohol in surfactant:cosurfactant weight-mixing ratios (K(m)) in the range 1:2 to 2:1. When hydrocarbon alcohols were used this clear region extended over a wide range of compositions and was confirmed by means of photon correlation spectroscopy (PCS) to contain microemulsion droplets in the propellant-rich part of the phase diagram. PCS studies performed in the presence of the water-soluble drug terbutaline sulfate showed that it was possible to solubilize the drug within water-in-propellant microemulsion droplets. These studies confirm for the first time that it is possible to prepare water-in-propellant 134a microemulsions using fluorinated ionic surfactants and to solubilize water-soluble drugs within these systems.