| 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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