Silica coated fullerenols: seeded growth of silica spheres under acidic conditions

Whitsitt, Elizabeth A.; Barron, Andrew R.

doi:10.1039/b212808j

Cited by 17 publications

(14 citation statements)

References 20 publications

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“…In the C 60 (OH) n seeding of LPD grown silica, the fullerenol hydroxides act as a reagent. 10 In the present case it appears that the surfactant offers a template role much in the same manner as we have previously observed for micelle templated LPD growth of silica spheres. 14 In the present case, the surfactant adsorbed onto the sidewalls of the SWNTs facilitates the growth of silica onto individual SWNTs.…”

Section: Synthesis and Characterization Of Sio 2 -Swntssupporting

confidence: 83%

LPD silica coating of individual single walled carbon nanotubes

et al. 2005

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Single walled carbon nanotubes (SWNTs) have been coated with fluorine-doped silica by liquid phase deposition (LPD) using a silica-H 2 SiF 6 solution and a surfactant stabilized solution of SWNTs. The coating of individual SWNTs versus small ropes is controlled by the choice of surfactant. Since the LPD reaction is performed close to the isoelectric point of the silica, some of the SiO 2 -SWNTs are fused together but the SWNTs remain individual in these composite structures. The SiO 2 -SWNTs have been characterized by SEM, TEM, Raman and IR spectroscopy, and XPS. Raman fluoresence is maintained even with coatings .50 nm. Using the relative intensity of the Raman G peak and the 8,3 SWNT fluorescence as a convenient measure of bundling, it may be shown that any decrease of fluoresence during growth is not due to changes in ionic strength or pH, as a consequence of addition of the LPD solution or the presence of HF as a side product in the deposition. The Raman D and G modes show no change in intensity, while the Fano line increases, both suggesting that no sidewall functionalization or proton adsorption of the SWNTs occurs during coating. The UV-visible-near infrared spectra shows a red shift in the first Van Hove transitions of the coated SWNTs inferring that the SWNTs in SiO 2 -SWNTs are in a more polarizable and inhomogeneous environment than that of surfactant solutions. Mats of SiO 2 -SWNT may be deposited onto silicon and gold substrates and through lithography may be patterned by etching off selected areas of the silica coating.

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Section: Synthesis and Characterization Of Sio 2 -Swntssupporting

confidence: 83%

LPD silica coating of individual single walled carbon nanotubes

et al. 2005

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“…Although the choice of fumed silica as a silicon source was chosen based upon our prior research, 22,25,26 it is important to determine if any form of silicon could initiate the formation of CBK-like material. To test this theory, silicic acid was selected as an alternative silicon source.…”

Section: Effect Of Silicon Concentration and Sourcementioning

confidence: 99%

“…Raman and XRD data confirmed the presence of calcium carbonate and silicon in the products. The increase in the amount of silica does not seem to affect the morphology of the structure but the size and chemical composition of the material does not match with ones found in either of the Although the choice of fumed silica as a silicon source was chosen based upon our prior research, 22,25,26 it is important to determine if any form of silicon could initiate the formation of CBK-like material. To test this theory, silicic acid was selected as an alternative silicon source.…”

Section: Effect Of Silicon Concentration and Sourcementioning

confidence: 99%

Synthesis of calcium–silica composites: A route toward an in vitro model system for calcific band keratopathy precipitates

Doostdar

Manrique

Hamill

et al. 2011

J Biomedical Materials Res

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Calcific band keratopathy (CBK) is a degenerative condition resulting in the deposition of calcium salts in the superficial layers of the cornea and causing significant visual disturbance and pain of the affected eye. Unfortunately, the amount of CBK precipitates recovered from the affected eye is very small therefore; it would be beneficial to prepare a synthetic material mimicking CBK material to further the development of therapeutics. Analyses of biological samples recovered from patients show the presence of silicon in addition to calcium, as well as a distinctive fused spherical morphology. This prompted us to study the reaction of various sources of silicon (fumed silica, silicic acid, and silicone oil) with CaCO(3) under a range of reaction conditions to gain an understanding of the formation of CBK. A silicon source alone was not found to be responsible for the fused spherical morphology, and a third component, a polar surfactant-like molecule such as sodium dodecyl sulfate or tetradecylphosphonic acid, was also required. The effects of silicon:calcium ratio and reaction time have been studied. The reaction of fumed silica with CaCO(3) in presence of sodium dodecyl sulfate results in the formation of spherical shapes resembling the structures and chemical composition observed in the eye samples, while no such structures were observed in the absence of silicon. Samples closely resembling human samples were also formed from the reaction of silicone oil with CaCO(3) in the presence of tetradecylphosphonic acid. Samples were characterized by SEM, XRD, and XPS and Raman spectroscopy.

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“…[5] Because of difficulties such as the low solubility and easy aggregation of fullerenes, these applications require functionalization with organic/inorganic composites including polymers, metals, and ceramics. [6][7][8][9] In this work, a reverse microemulsion method with a nonionic surfactant was used, for the first time, to form fullerene-silica hybrid materials (Figure 1 a). C 60 fullerenes were encapsulated in a microemulsion with the help of the cosurfactant n-hexanol, and were then incorporated into the silica network by the addition of triethyl orthosilicate (TEOS) as a silica precursor and ammonium hydroxide (NH 4 OH) as a catalyst.…”

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confidence: 99%