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Titolo:
Transformation of CdS colloids: Sols, gels, and precipitates
Autore:
Gacoin, T; Lahlil, K; Larregaray, P; Boilot, JP;
Indirizzi:
Ecole Polytech, CNRS, UMR 7643, Grp Chim Solide,Lab Phys Mat Condensee, F-91128 Palaiseau, France Ecole Polytech Palaiseau France F-91128 ensee, F-91128 Palaiseau, France
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 42, volume: 105, anno: 2001,
pagine: 10228 - 10235
SICI:
1520-6106(20011025)105:42<10228:TOCCSG>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
E = S; CLUSTERS; GELATION; CRYSTAL; SILICA; SIZE; NMR; AGGREGATION; SCATTERING; PARTICLES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Boilot, JP Ecole Polytech, CNRS, UMR 7643, Grp Chim Solide,Lab Phys Mat Condensee, F-91128 Palaiseau, France Ecole Polytech Palaiseau France F-91128 128 Palaiseau, France
Citazione:
T. Gacoin et al., "Transformation of CdS colloids: Sols, gels, and precipitates", J PHYS CH B, 105(42), 2001, pp. 10228-10235

Abstract

Highly concentrated CdS colloids (about 30 wt %) are prepared in acetone through the grafting of 4-fluorophenylthiol at their surface. F-19 NMR measurements show that the controlled oxidation by an aqueous solution of hydrogen peroxide leads to a mixture of dithiol and fluorosulfonate species. Aggregation of particles produces either transparent gels or opaque precipitates, depending on the nature and the concentration of the oxidant. The sol-gel transformation results from an aggregation mechanism, which requires the release of surface groups because of their interaction with water molecules. Considering the formation of mass-fractal clusters, small-angle X-ray scattering measurements show, at least in the first steps, that the growth kinetics is in agreement with the usual reaction limited cluster aggregation mechanism previously observed in the silica system. This can be followed by a saturation effect, enhanced at low water concentration, which is due to the poisoning of the surface by chemical groups produced by oxidation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/04/20 alle ore 03:49:04