Publication Type Journal Article
Title Phase behaviour of oleanolic acid/stearyl stearate binary mixtures in bulk and at the air-water interface
Authors Ana C. T. Teixeira Ana R. Garcia Laura M. Ilharco Amélia Gonçalves da Silva Anabela Fernandes
Groups MET
Journal CHEMISTRY AND PHYSICS OF LIPIDS
Year 2009
Month July
Volume 160
Number 1
Pages 45-57
Abstract The solid-liquid phase behaviour of oleanolic acid (OLA)/stearyl stearate (SS) was investigated by differential scanning calorimetry and polarizing optical microscopy. A eutectic type diagram, with the eutectic composition close to pure SS was obtained. Complementary studies by NMR, X-ray diffraction (XRD) and diffuse reflectance infrared Fourier transform (DRIFr) spectroscopy were performed. A mutual influence was detected in mixtures: the low melting form of SS is favoured at low OLA molar fractions (X-OLA) and spherulitic structures appear at high X-OLA and high temperature. Additionally, H-bonding between OLA carbonyl groups increases in the presence of SS. The study of OLA/SS by the Langmuir method and Brewster angle microscopy revealed the organization at the air-water interface: OLA interacts with water in the first layer, while SS is completely segregated to the upper layer for X-OLA > 0.3, and it distributes in the first and upper layers for X-OLA < 0.3. (C) 2009 Elsevier Ireland Ltd. All rights reserved.
DOI http://dx.doi.org/10.1016/j.chemphyslip.2009.04.001
ISBN
Publisher ELSEVIER IRELAND LTD
Book Title
ISSN 0009-3084
EISSN
Conference Name
Bibtex ID ISI:000267584700004
Observations
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