Characterizing colloidal structures of pseudoternary phase diagrams formed by oil/water/amphiphile systems

Alany, RG, Tucker, IG, Davies, NM and Rades, T (2001) Characterizing colloidal structures of pseudoternary phase diagrams formed by oil/water/amphiphile systems. Drug Development And Industrial Pharmacy, 27 1: 31-38.


Author Alany, RG
Tucker, IG
Davies, NM
Rades, T
Title Characterizing colloidal structures of pseudoternary phase diagrams formed by oil/water/amphiphile systems
Journal name Drug Development And Industrial Pharmacy   Check publisher's open access policy
Publication date 2001
Sub-type Article
DOI 10.1081/DDC-100000125
Volume number 27
Issue number 1
ISSN 0363-9045
Start page 31
End page 38
Total pages 8
Place of publication New York
Publisher Marcel Dekker Inc
Language eng
Abstract Two pseudoternary phase diagrams were constructed using ethyl oleate, water and a surfactant blend containing poly (oxyethylene 20) sorbitan monooleate and sorbitan monolaurate with or without the cosurfactant 1-butanol. Two colloidal regions were identified in the cosurfactant;free phase diagram; a microemulsion (ME) and a region containing lamellar liquid crystals (LC). The addition of 1-butanol increased the area in which systems formed microemulsions and eliminated the formation of any liquid crystalline phases. Samples that form the colloidal regions of both systems were investigated by freeze-fracture transmission electron microscopy and by viscosity and conductivity measurements. The three techniques were compared and evaluated as characterisation tools for such colloidal systems and also to identify transitions between the colloidal systems formed A droplet ME was present at a low water volume fraction (phi (w)) in both systems (phi (w) < 0.15) as revealed by electron microscopy. At higher (w) values, LC structures were Observed in micrographs of samples taken from the cosurfactant-free system while the structure of samples from the cosurfactant-containing system was that of a bicontinuous ME. The viscosity of both systems increased with increasing phi (w) to 0.15 and flow was Newtonian. However; formation of LC in the cosurfactant-free system resulted in a dramatic increase in viscosity that was dependent on phi (w) and a change to pseudoplastic flow. In contrast, the viscosity of the bicontinuous ME was independent of phi (w). Three different methods were used to estimate the percolation threshold from the conductivity data far the cosurfactant-containing system. The use of nonlinear curve fitting was found to be most useful yielding a value close to 0.15 for the phi (w).
Keyword Chemistry, Medicinal
Pharmacology & Pharmacy
conductivity
electron microscopy
microemulsion
percolation threshold
viscosity
Understanding Microemulsion Microstructure
Micro-emulsions
Percolation
Water
Conductivity
Transport
Electron
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article
Collection: School of Pharmacy Publications
 
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Created: Fri, 25 Jan 2008, 15:21:08 EST