The porous structure of self-supporting pressed silica discs I. Infrared spectroscopic studies

Tyler, A. J.; Hambleton, F. H.; Hockey, J. A.

doi:10.1016/0021-9517(69)90367-4

Cited by 29 publications

(4 citation statements)

References 5 publications

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“…Absolute integrated intensities of the NMR signals for a mixture consisting of known weights of silica and silicone rubber enable one to evaluate the surface densities of hydroxyls. Based on information derived from spectra such as those in Figures f and f, from the integral ratio of the Cab-O-Sil silica and silicone rubber signals and from the known surface area (325 m 2 /g) of the Cab-O-Sil silica, the concentration of silanol groups on a HS-5 Cab-O-Sil sample from which physisorbed water has been removed is found to be 2.8 ± 0.3 OH/(nm) 2 , which is in good agreement with the corresponding results obtained by other techniques. − …”

Section: Resultssupporting

confidence: 80%

“…The concentration of silanol groups on the silica surface is an issue that has been explored since the 1960's, based on a variety of methods. − The silanol concentration for Aerosil, another fumed silica, is well-known to be about 3 OH/(nm) 2 , a value obtained by quite a few investigations. − Use of silicone polymer as a 1 H NMR intensity standard in this Cab-O-Sil silica study provides another very useful way of calculating hydroxyl densities on surfaces . Absolute integrated intensities of the NMR signals for a mixture consisting of known weights of silica and silicone rubber enable one to evaluate the surface densities of hydroxyls.…”

Section: Resultsmentioning

confidence: 99%

“…Because the widespread utility of amorphous silicas, e.g., in sorption, heterogeneous catalysis, and composite materials, is largely a result of their surface properties, studies of the structures, chemistry, and properties of a variety of fumed silica surfaces have been carried out by many researchers for many years. − Careful analysis by a variety of methods has shown that the surface reactivity of a silica depends substantially on the quantity and structural environment of its surface hydroxyl groups, which in turn depend on the origin of the silica and its storage and treatment conditions − …”

Section: Introductionmentioning

confidence: 99%

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The Fumed Silica Surface: A Study by NMR

1996

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High-resolution solid-state NMR techniques were used to investigate the surface structure of Cab-O-Sil fumed silica. 1H NMR results obtained from CRAMPS, MAS-only and relaxation studies reveal the existence of both hydrogen-bonded silanols and isolated silanols on the Cab-O-Sil surface. A systematic dehydration study of fumed silica was carried out, with results on the quantity of each type of silanol on the surface at various dehydration stages. 29Si CP-MAS experiments, including CP spin dynamics studies and various other relaxation studies, were employed to probe hydrogen bonding and the local structural environments of various hydroxyl groups of silica surfaces. 29Si CP-MAS experiments on water-treated and deuterium-exchanged Cab-O-Sil indicate the existence of interparticle silanols and internal silanols in fumed silica. 1H and 29Si NMR show that for fumed silica both isolated and hydrogen-bonded silanols are present on the surface of an untreated sample, in contrast to the case of silica gel, where all silanols of an untreated sample are hydrogen bonded.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Fumed Silica Surface: A Study by NMR

1996

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“…The broad band is identified with hydrogen-bonded OH surface groups, physisorbed water, and other impurities on the silica surface. The sharp band at 3745 cm-1 has been assigned to the free surface OH group attached to Si as Si-O-H (14)(15)(16)(25)(26)(27). The weak kink appearing at 988 cm 1 (Fig.…”

Section: Surface Modesmentioning

confidence: 99%

Surface and Bulk Infrared Modes of Crystalline and Amorphous Silica Particles: A Study of the Relation of Surface Structure to Cytotoxicity of Respirable Silica

Pandurangi¹,

Seehra²,

Razzaboni³

et al. 1990

Environmental Health Perspectives

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Surface IR (infrared) modes of crystalline and fumed (amorphous) silica particles, calcined at temperatures up to 1095°C, have been studied by Fourier transform infrared spectroscopy. The ability of these same particles to lyse cells has been measured by a hemolysis protocol. The untreated crystalline and amorphous materials differ by a factor of 40 in specific surface area, and the intensity per unit mass ofthe sharp surface silanol band near 3745 cm-' in the amorphous material is an order of magnitude larger than in the crystalline material. A similar difference is observed in the lysing potential of the two materials. The intensity of the silanol band increases after calcination for both materials, reaching peak values near 500°C, followed by a dramatic drop at higher calcination temperatures, and reaching negligible values for materials calcined near 1100C. The lysing potential data follow essentially the same pattern for both crystalline and fumed silica. These results are consistent with the hypothesis that the surface silanol groups are involved in cell lysis. Further experiments are suggested to evaluate the relationship between the surface structure of silica particles and their potential cytotoxicity.

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H Bonding Properties of Hydroxyl Held on the Surface of Silica

Sempels

Rouxhet

1975

Bulletin des Soc Chimique

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ABSTRACT. The H bonding properties of silica gel surface hydroxyl have been studied by adsorbing series of organic compounds which are weak H bond acceptors and by observing the OH stretching band. While the data are consistent with the charge transfer model of H bond, a critical examination shows that their support to this theory, as well as the support of similar data reported for solutions, is not really significant. All the results, and particularly relationships found between absorption coefficients, show a complete similarity between the characteristics of H bonds formed on the solid surface and in solutions.

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The porous structure of self-supporting pressed silica discs I. Infrared spectroscopic studies

Cited by 29 publications

References 5 publications

The Fumed Silica Surface: A Study by NMR

The Fumed Silica Surface: A Study by NMR

Surface and Bulk Infrared Modes of Crystalline and Amorphous Silica Particles: A Study of the Relation of Surface Structure to Cytotoxicity of Respirable Silica

H Bonding Properties of Hydroxyl Held on the Surface of Silica

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