Insights into the formation mechanism of imogolite from a full-range observation of its sol-gel growth

Du, Peixin; Yuan, Peng; Thill, Antoine; Annabi-Bergaya, Faïza; Liu, Dong; Wang, Shun

doi:10.1016/j.clay.2017.09.021

Cited by 33 publications

(45 citation statements)

References 50 publications

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“…Concerning imogolite nanotubes, although their formation mechanism has been extensively investigated and described in recent literature [66], their stability in aqueous suspension was not deeply investigated. On the other hand, Paineau et al [9] firstly observed that INTs show a liquid-crystal phase, columnar in particular, at low concentrations (≈0.3%) with low visco-elasticity and that is aligned under an electric field.…”

Section: Imogolitementioning

confidence: 99%

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

et al. 2018

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Featured Application: The review is focused on the stabilization of nanotubular materials in solvent media. This aspect is a key starting point for any application of nanotube-based formulations for pharmaceutical and industrial applications.Abstract: Inorganic nanotubes are attracting the interest of many scientists and researchers, due to their excellent application potential in different fields. Among them, halloysite and imogolite, two naturally-occurring aluminosilicate mineral clays, as well as boron nitride nanotubes have gained attention for their proper shapes and features. Above all, it is important to reach highly stable dispersion in water or organic media, in order to exploit the features of this kind of nanoparticles and to expand their applications. This review is focused on the structural and morphological features, performances, and ratios of inorganic nanotubes, considering the main strategies to prepare homogeneous colloidal suspensions in various solvent media as special focus and crucial point for their uses as nanomaterials.

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Section: Imogolitementioning

confidence: 99%

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

et al. 2018

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“…Transformation of imogolite by decylphosphonic acid patterns. [31][32][33] Fitting the obtained curve with the scattering pattern of a hollow cylinder gives an outer tube radius of 2.8 nm, which is a typical value for synthetic dispersed imogolite.…”

Section: Resultsmentioning

confidence: 91%

“…5 Lastly, the doublet appearing at 988 cm −1 /941 cm −1 , which is related to the asymmetric stretching mode of the isolated SiO 4 tetrahedra and is typical for the tubular shape of imogolite. 6,31,[35][36][37] After reaction with DPA, all the characteristic regions of imogolite are retrieved in the between ODPA and germanium imogolite. [14][15]19 The spectrum of sample B suggests a rather low amount of residual imogolite due to the modification of the typical hydroxyl, Al-O and Si-O bands.…”

Section: Ftirmentioning

confidence: 99%

“…The obtained results challenge the commonly used scheme of grafted imogolite, where the phosphonic acid reacts with OH groups on the external wall of imogolite and forms covalent bonds by condensation. [18][19][21][22] IR, 31 The basis for this reactivity is the surface chemistry of imogolite, which is similar to gibbsite. The tube wall is covered in bridging Al 2 (µ-OH) groups that correspond to the crystal face of gibbsite, while the terminal points have Al-OH / Al-OH 2 + groups, similar to the crystal edges of gibbsite.…”

Section: Degradation Versus Surface Modificationmentioning

confidence: 99%

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Partial Transformation of Imogolite by Decylphosphonic Acid Yields an Interface Active Composite Material

et al. 2019

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The phosphonic acid moiety is commonly used as an anchoring group for the surface modification of imogolite. However, the impact of the reaction on its structure has never been clearly analyzed before.We study the reaction of imogolite and decylphosphonic acid by combining infrared spectroscopy, X-ray scattering, scanning electron microscopy, transmission electron microscopy and solid-state nuclear magnetic resonance spectroscopy. Instead of a surface functionalization, we observe the formation of a lamellar phase interconnected with imogolite bundles. Although we find no evidence for grafted imogolite tubes, we observe the expected dispersion characteristics and stabilization of water in toluene emulsions described in literature. Based on the surface chemistry of imogolite we propose an explanation for the observed reactivity and link the structural features of the obtained composite material to its dispersibility in toluene and its observed properties at the toluene-water interface.

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“…The wall of Allo consists of a curved gibbsite-like sheet with Al2-µOH groups that are, on the inner side, substituted by orthosilicate groups. This local structure with a Si/Al molar ratio of 0.5 also occurs in imogolite (Imo, a nanotubular polymorph of Allo) and thus is called an imogolite local structure (ImoLS) [16]. Unlike Imo whose Si/Al molar ratio is 0.5, Allo has a Si/Al molar ratio of 0.5−1.0, and the excess Si is attached to the ImoLS in the form of oligomeric silicate, contributing to the low structural order of Allo.…”

Section: Introductionmentioning

confidence: 99%

Tailoring structure and surface chemistry of hollow allophane nanospheres for optimization of aggregation by facile methyl modification

Thill

Yuan

et al. 2020

Applied Surface Science

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Allophane, an earth-abundant and easy-to-be-synthesized hollow nanospherical material, readily loses its unique pore structure via irreversible aggregation of particles upon drying, which mainly results from capillary stress in the unsaturated inner cavity. To tackle this problem, we develop a strategy for tailoring the capillary stress and thus the aggregation state of allophane by introducing methyl moieties onto the inner surface during preparation. Combined spectroscopic results verified the formation of methyl-allophane with methyl groups only on its inner surface. The presence of a reflection at approximately 33 Å in the X-ray diffraction pattern, ascribed to the interference between particles, indicated an increased structural order in methyl-allophane. The thermal analysis data revealed a decrease of the inner-surface hydrophilcity. The Brunauer-Emmett-Teller (BET) specific surface area increased from 269 to 523 m 2 /g after methyl modification. An aggregation model, in contrast with that of allophane, was proposed based on the microscopic and small-angle X-ray scattering results to explain these observed changes. This work exhibited that substitution of silanol by methyl on the inner surface of allophane leads to improvement of structural order by eliminating the presence of oligomeric silicates and decreases the hydrophilicity, resulting in the reduction of the capillary stress in the inner cavity and thus the inhibition of irreversible aggregation of particles during drying. The insight into the mechanisms underneath the above mentioned changes upon methyl modification unraveled in this work is helpful for addressing the common aggregation issue of other nanomaterials.

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Insights into the formation mechanism of imogolite from a full-range observation of its sol-gel growth

Cited by 33 publications

References 50 publications

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

Partial Transformation of Imogolite by Decylphosphonic Acid Yields an Interface Active Composite Material

Tailoring structure and surface chemistry of hollow allophane nanospheres for optimization of aggregation by facile methyl modification

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