| Titre : |
Unexpected electronic effects on benzotriazole UV absorber photostability : Mechanistic implications beyond excited state intramolecular proton transfer |
| Type de document : |
texte imprimé |
| Auteurs : |
Joseph C. Suhadolnik, Auteur ; Anthony D. DeBellis, Auteur ; Carmen Hendricks-Guy, Auteur ; Revathi Lyengar, Auteur ; Mervin G. Wood, Auteur |
| Année de publication : |
2002 |
| Article en page(s) : |
p. 55-61 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Tags : |
Etude expérimentale Acrylique dérivé polymère Thermoplastique Mélamine résine Transfert proton Réaction intramoléculaire Etat excité Effet électronique Benzotriazole Absorbant UV Adjuvant Stabilité photochimique Peinture Matériau revêtement Dégradation Polymère |
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Electron withdrawing groups at the 5-position of beazotriazole ultraviolet absorbers (UVA) surprisingly improve photopermanence despite weakening the intramolecular hydrogen bond believed to be responsible for photostability. These results, encountered in coatings, thermplastics, and solvents, contradict the assumption from the widely accepted view of UVA photostability that a stronger H-bond would generate a more stable UVA. Calculations suggest the involvement of a conical intersection in benzotriazole excited state deactivation and support a significant role for charge transfer. Modifications to the traditional model of UVA photostability are discussed which more fully consider electronic factors and molecular motions other than H-transfer. |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5681 |
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 924 (01/2002) . - p. 55-61
Aller sur edunet
Accueil
Unexpected electronic effects on benzotriazole UV absorber photostability in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 924 (01/2002)
