Sonogels and derived materials

Blanco, E.; Esquivias, L.; Litrán, R.; Piñero, Manuel; Ramírez‐del‐Solar, M.; Rosa–Fox, N. de la

doi:10.1002/(sici)1099-0739(199905)13:5<399::aid-aoc825>3.0.co;2-a

Cited by 93 publications

(54 citation statements)

References 98 publications

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“…Energy from cavitation is released in the form of shockwaves and jets which may fragment nearby particles, or cause them to melt and fuse through high-speed collisions. 367 Perhaps surprisingly, self-assembly can take place in such an environment, [368][369][370] and may even proceed at a lower concentration, higher temperature or faster rate than would be possible under milder conditions. 129,371,372 Moreover, the resulting aggregates may prove unusual, with structures or physical properties that would be difficult to achieve by other methods.…”

Section: Mechanically Induced Gelationmentioning

confidence: 99%

Gels with sense: supramolecular materials that respond to heat, light and sound

2016

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. (2016) 'Gels with sense : supramolecular materials that respond to heat, light and sound.', Chemical society reviews., 45 (23). pp. 6546-6596. Further information on publisher's website:https://doi.org/10.1039/C6CS00435KPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Advances in the field of supramolecular chemistry have made it possible, in many situations, to reliably engineer soft materials to address a specific technological problem. Particularly exciting are "smart" gels that undergo reversible physical changes on exposure to remote, non-invasive environmental stimuli. This review explores the development of gels which are transformed by heat, light and ultrasound, as well as other mechanical inputs, applied voltages and magnetic fields. Focusing on small-molecule gelators, but with reference to organic polymers and metal-organic systems, we examine how the structures of gelator assemblies influence the physical and chemical mechanisms leading to thermo-, photo-and mechano-switchable behaviour. In addition, we evaluate how the unique and versatile properties of smart materials may be exploited in a wide range of applications, including catalysis, crystal growth, ion sensing, drug delivery, data storage and biomaterial replacement.

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Section: Mechanically Induced Gelationmentioning

confidence: 99%

Gels with sense: supramolecular materials that respond to heat, light and sound

2016

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“…Sonication is an alternative method to stimulate the hydrolysis of the alkoxide without using alcoholic solvents in the sol-gel process [13,14]. Strong ultrasound action (20-100 kHz) induces chemical reactions and/or enhances their rate [15].…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic preparation of mesoporous silica using pyridinium ionic liquid

Putz

Len

Ianăși

et al. 2016

Korean J. Chem. Eng.

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2Mesoporous silica matrices have been prepared via classic acid catalyzed and sono-catalyzed sol-gel routes. Tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) were used as silica precursors, and N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]) was employed as cosolvent and pore template. The ionic liquid (IL) to silica mole ratio was varied between 0.007 and 0.07. Nitrogen adsorption-desorption and small-angle neutron scattering measurements have been used to characterize the obtained materials. The ionic liquid played the role of catalyst that affected the formation of the primary xerogel particles, and changed the porosity of the materials. Ultrasound treatment resulted in microstructure change on the level of the colloid particle aggregates. In comparison with IL containing xerogels, the IL containing sonogels show increased pore diameter, bigger pore volumes and diminished surface areas.

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“…1b). This related to the fact that TEOS is known to favour the formation of three-dimensional network of linked oxide particles in the gel leading to a proper pore structure in the annealed composites [21]. The surface of 10 at% SiO 2 -90 at% SnO 2 films is significantly roughened in the whole region of spatial wavelengths compared to SnO 2 films deposited by the same procedure without adding TEOS to the solution.…”

Section: Methodsmentioning

confidence: 99%

Metal-oxide-based nanocomposites comprising advanced gas sensing properties

Пономарева

Мошников

Glöß

et al. 2012

J. Phys.: Conf. Ser.

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Abstract. Using the sol-gel technique, nanocomposite SiO 2 -SnO 2 thin films comprising a designed hierarchical pore structure were prepared on cost-efficient oxidized silicon substrates. These films exhibit advanced gas sensing properties both for reducing gases and oxygen due to an efficient analyte transport by mesoporores. IntroductionGas sensitivity of metal oxide gas sensors increases rapidly when the dimensions of oxide sensing materials become comparable or smaller than the typical thickness of the electron depletion layer [1]. Therefore, nanosized materials exhibit outstanding properties in sensor application, particularly low operation temperature and high sensitivity, attributed to their large surface area to volume ratio.Hierarchical structures are higher dimensional structures composed of many, lower dimensional building blocks. Because they are generally larger than the individual nanostructures, their van der Waals attraction is relatively weak. On the other hand, hierarchical microstructures provide an effective gas diffusion path via well aligned mesoporous structures without sacrificing a high surface area [2]. Consequently, they exhibit high gas sensitivity and fast gas response. Hierarchical nanostructures for gas sensors were prepared by vapour phase growth, hydrothermal or hydrothermal/solvothermal reactions [2], by electrospinning and subsequent oxygen plasma etching [3], by ultrasonic spray pyrolysis [4], by flame-spray-pyrolysis [5,6], and by pulsed laser deposition techniques [7]. Well defined hierarchical pore structures were prepared by sol-gel method in alkoxyderived silica systems [8] as well as in aluminium salt solutions [9] utilizing a phase separation mechanism as a pore forming principle. Recently, one of our laboratories has applied this approach for the fabrication of SnO 2 -SiO 2 composites comprising hierarchical macro-, meso-and micropores (according to IUPAC notation [10]). This minimises the build up of thermal stresses during sensor fabrication and, therefore, improves adhesion. Moreover, our technology is based on inexpensive precursors such as SnCl 2 and tetraethylorthosilicate (TOES). In the first case, advantages compared to alkoxides are besides the precursor costs a reduced sensitivity of the precursor to heat, moisture and light, and an improved time stability of the sol against the increase in viscosity. On the other hand, the presence of Cl -increases the gelling time. In this work, we investigate gas sensing properties of sol-gel deposited nanocrystalline SnO 2 -SiO 2 composites in relation to their microstructure and demonstrate gas sensitivities at the state-of-art level.

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Sonogels and derived materials

Cited by 93 publications

References 98 publications

Gels with sense: supramolecular materials that respond to heat, light and sound

Gels with sense: supramolecular materials that respond to heat, light and sound

Ultrasonic preparation of mesoporous silica using pyridinium ionic liquid

Metal-oxide-based nanocomposites comprising advanced gas sensing properties

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