[article]
| Titre : |
The characterisation of surface area and surface heterogeneity profiles of hair by inverse gas chromatography |
| Type de document : |
texte imprimé |
| Auteurs : |
Frank Thielmann, Auteur ; Duncan Pearce, Auteur ; Yash K. Kamath, Auteur |
| Année de publication : |
2002 |
| Article en page(s) : |
p. 189-193 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Caractérisation
Cheveux -- analyse
Cheveux -- Anatomie
Chromatographie en phase inverseLa chromatographie en phase inverse est un type de chromatographie. La base d'une phase inverse est une phase normale sur laquelle des chaînes alkyles (ou autres selon la polarité recherchée) ont été greffées au niveau des groupes silanols (end-capping).
En général, la phase stationnaire est majoritairement composée de petites particules de silice sur lesquelles on a greffé des fonctions chimiques, le plus souvent de chaines alkyles à 8 ou 18 atomes de carbones. Les fonctions silanols (Si-OH) qui subsistent engendrent des interactions hydrophiles parasites, qui rendent les résultats non reproductibles surtout pour les molécules basiques. Pour éviter cela, la surface de la silice est généralement recouverte par une fonction méthyle et les fonctions silanols ne sont plus libres mais sous la forme (Si-O-CH3), c'est cette étape que l'on appelle "end-capping". Les fonctions chimiques utilisées pour le "end-capping" peuvent toutefois être de nature très diverses et les colonnes de dernières générations résistant à des pH extrêmes sont généralement "end-capped" avec des fonctions proposant une plus grande gène stérique, tel que le tert-butyle (Si-O-C(CH3)3).
Selon le taux de greffage, on obtient une plus ou moins grande résolution.
Cette phase est dite "inverse" car de polaire et hydrophile (sans les "greffes"), la phase devient apolaire et hydrophobe.
Conditionneurs (cosmétique)
Energie de surface
Oxydoréduction
Traitement chimique
|
| Index. décimale : |
668.5 Parfums et cosmétiques |
| Résumé : |
In the present paper the surface areas and adsorption potential distributions of nine different hair samples have been determined by Inverse Gas Chromatography (IGC). These samples were subjected to chemical grooming procedures followed by conditioner treatments both of which alter the surface energy of hair. Since surface energy affects the strength of adsorption of molecules on the surface, this can be characterized by determining the adsorption potential distribution of the surface of hair using specific probe molecules. The distribution function reflects the energetic heterogeneity profile of a surface and provides interesting information on the nature and population of surfaces sites of different interaction energy. In this study IGC is shown to be a fast and accurate technique for the determination of these distribution functions. The data can be used to explain the adsorption behavior of various surfactants and conditioners from different formulations and how these surface deposits alter the energy of the fiber surface. The results indicate that chemical reactions such as bleaching (oxidation) and perming (reduction) increase the surface energy of the fiber by increasing the number of acidic anionic groups in the surface of hair and consequently increase the adsorption potential of the surface. The energy of the resulting surface depends on the orientation of adsorbed molecules. For example, coverage of anionic surface by cationic conditioner molecules can result in a decrease in the surface energy because of the projection of lipid chain of the surfactant away from the surface. Although IGC has been used in the study of surface energetics of polymers and fibers, its use in unraveling the surface energetics of hair, especially when hair is subjected to damaging grooming treatments and treatments which alleviate such damage, is novel. This is especially true of bleaching and perming which introduce acidic sites in the hair and treatment with surfactants and conditioners which adsorb on these sites and leave a protective residue in the hair. These residues alter the surface energy of hair. The changes that occur on the outer surface can be determined by wettability measurements. However, the changes that occur by alyerations in porosity (as in perming) and penetration of low molecular weight materials such as surfactants and humectants, and their adsoprtion on the internal surface of hair can be determined only by methods like IGC. The method can be very sensitive depending on the selection of appropriate probe molecules. |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10646 |
in IFSCC MAGAZINE > Vol. 5, N° 3 (07-08-09/2002) . - p. 189-193
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The characterisation of surface area and surface heterogeneity profiles of hair by inverse gas chromatography in IFSCC MAGAZINE, Vol. 5, N° 3 (07-08-09/2002)
