Highly fluorinated silica obtained by direct F<sub>2</sub>-gas fluorination: stability and unprecedented fluorosilicate species revealed by solid state NMR investigations
| hal.structure.identifier | Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB] | |
| dc.contributor.author | LATASTE, Emilie | |
| hal.structure.identifier | Fédération RMN du Solide à Hauts Champs [FRMN-SHC] | |
| dc.contributor.author | LEGEIN, Christophe | |
| hal.structure.identifier | Laboratoire de physique de l'état condensé [LPEC] | |
| dc.contributor.author | BODY, Monique | |
| hal.structure.identifier | Fédération RMN du Solide à Hauts Champs [FRMN-SHC] | |
| dc.contributor.author | BUZARÉ, Jean-Yves | |
| hal.structure.identifier | Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB] | |
| dc.contributor.author | TRESSAUD, Alain | |
| hal.structure.identifier | Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB] | |
| dc.contributor.author | DEMOURGUES, Alain | |
| dc.date.issued | 2009 | |
| dc.identifier.issn | 1932-7447 | |
| dc.description.abstractEn | The direct F<sub>2</sub>-gas fluorination of mesoporous silica is a unique method leading to high fluorinated (up to 13 wt % F) and homogeneous powder with a controlled amount of grafted fluorine. Thermogravimetric analysis coupled with mass spectrometry for water, hydroxyl, and fluorine groups have allowed concluding that low fluorine-grafted silicas are thermically stable up to 550 °C whereas high fluorine-grafted silicas start to decompose from 250 °C with departure of SiF<sub>4</sub> species. Water adsorption measurements have demonstrated the hydrophobic character of fluorinated silica and proved that direct fluorination is a way to control the hydrophilic−hydrophobic balance of silica. Pristine and fluorinated silicas have been studied by <sup>19</sup>F and <sup>1</sup>H MAS, and <sup>1</sup>H−<sup>29</sup>Si and <sup>19</sup>F−<sup>29</sup>Si CP-MAS NMR spectroscopies. NMR measurements have revealed various tetrahedral (O<sub>2/2</sub>SiF<sub>2</sub>, O<sub>3/2</sub>SiF) and pentahedral (O<sub>4/2</sub>SiF) fluorosilicate species previously observed in moderately fluorinated silica, and two unprecedented pentahedral species occurring in these highly fluorinated silica: O<sub>3/2</sub>SiF<sub>2</sub> and O<sub>2/2</sub>SiF<sub>3</sub> (δ<sub>iso</sub>(<sup>19</sup>F) = −143.5 and −136.5 ppm; δ<sub>iso</sub>(<sup>29</sup>Si) = −124 and −132 ppm, respectively). The occurrence of these unusual species, thanks to the coupling between the redox mechanism and an etching phenomenon provoked by direct F<sub>2</sub>-gas fluorination, should explain the thermal stability as well as the water affinity of fluorinated silica. | |
| dc.language.iso | en | |
| dc.publisher | American Chemical Society | |
| dc.title.en | Highly fluorinated silica obtained by direct F<sub>2</sub>-gas fluorination: stability and unprecedented fluorosilicate species revealed by solid state NMR investigations | |
| dc.type | Article de revue | |
| dc.identifier.doi | 10.1021/jp9087628 | |
| dc.subject.hal | Chimie/Matériaux | |
| bordeaux.journal | Journal of Physical Chemistry C | |
| bordeaux.page | 18652-18660 | |
| bordeaux.volume | 113 | |
| bordeaux.issue | 43 | |
| bordeaux.peerReviewed | oui | |
| hal.identifier | hal-00438500 | |
| hal.version | 1 | |
| hal.popular | non | |
| hal.audience | Internationale | |
| hal.origin.link | https://hal.archives-ouvertes.fr//hal-00438500v1 | |
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