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Solid-state NMR characterization of the surfactant-silica interface in templated silicas: acidic versus basic conditions

Baccile, Nicki and Laurent, Guillaume and Bonhomme, Christian and Innocenzi, Plinio and Babonneau, Florence (2007) Solid-state NMR characterization of the surfactant-silica interface in templated silicas: acidic versus basic conditions. Chemistry of materials, Vol. 19 (6), p. 1343-1354. eISSN 1520-5002. Article.

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DOI: 10.1021/cm062545j

Abstract

A combination of one-dimensional and two-dimensional solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) experiments has been used to investigate the hybrid organic-inorganic interfaces in surfactant templated silicas. Samples prepared with cetyltrimethylammonium bromide (CTAB) under acidic (HCl) and basic (NaOH) conditions have been compared. The use of sequences based on the 29Si-1H heteronuclear dipolar interactions allows us to selectively filter the NMR response of the protons close to the Si surface sites showing directly the clear difference between the two systems. The basic sample is characterized by a small amount of Si-OH groups and a short distance between the Si-O- surface groups and the surfactant polar head group, while the acidic sample exhibits a silanolrich surface with a longer distance between the Si surface sites and the polar head groups. The nature of the interface induces consequent differences in the structure of the adsorbed water layers present at the interface, and this has been revealed by near-infrared experiments, as well as 1H MAS NMR spectra recorded on dehydrated and partially rehydrated samples. One objective of this work was also to show that the use of standard solid-state NMR conditions (magnetic field of 7 T and magic angle spinning frequency of less than 15 kHz) can be largely sufficient to obtain extremely valuable information regarding the silica-surfactant interfaces.

Item Type:Article
ID Code:1245
Status:Published
Refereed:Yes
Uncontrolled Keywords:Magic angle spinning nuclear magnetic resonance (MAS NMR), cetyltrimethylammonium bromide (CTAB), 29Si-1H heteronuclear dipolar interactions, silica−surfactant interfaces
Subjects:Area 09 - Ingegneria industriale e dell'informazione > ING-IND/22 Scienza e tecnologia dei materiali
Divisions:002 Altri enti e centri di ricerca del Nord Sardegna > INSTM-Consorzio Interuniversitario Nazionale per la Scienza e la Tecnologia dei Materiali, Unità di ricerca di Sassari
001 Università di Sassari > 01 Dipartimenti > Architettura e pianificazione
Publisher:American Chemical Society
eISSN:1520-5002
Deposited On:18 Aug 2009 10:04

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