A new route to aerogels: Monolithic silica cryogels

Pons, Anne-Cécile; Casas, Lluı̀s; Estop, E.; Molins, Elı́es; Harris, Kenneth David Maclean; Xu, Mingcan

doi:10.1016/j.jnoncrysol.2011.10.031

Cited by 68 publications

(33 citation statements)

References 37 publications

(43 reference statements)

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“…Pons et al [91] synthesised silica cryogels with properties similar to those of silica aerogels, particularly in terms of monolithicity, density, porosity and specific surface area. This similarity can be explained by high pressure produced by ice crystallites onto thin residual liquid films between these crystallites that is similar to high-pressure condition used on synthesis of aerogels.…”

Section: Types Of Cryogel Based Composite and Hybrid Materialsmentioning

confidence: 99%

“…This similarity can be explained by high pressure produced by ice crystallites onto thin residual liquid films between these crystallites that is similar to high-pressure condition used on synthesis of aerogels. The textural characterisation of silica cryogels was based on nitrogen adsorption isotherms appropriately analysed, SEM images (with no quantitative analysis), and the structure was also analysed using 29 Si MAS NMR and FTIR spectra [91]. Hybrid SBA-15/carbon cryogel composites were prepared by sol-gel polycondensation of resorcinol and formaldehyde followed by freeze drying, and subsequent pyrolysis [92], and characterised using nitrogen adsorption, XRD and SEM (images were not treated) methods.…”

Section: Types Of Cryogel Based Composite and Hybrid Materialsmentioning

confidence: 99%

“…In recently published papers, the characterisation of solid composite cryogels with silica [228], carbon [229,230], carbon/carbon [231] or carbon/silica composite [92] Yun et al [247] synthesised polyacrylamide based supermacroporous cryogel beads with a narrow particle size distribution at average particle size around 1 mm with high porosity of 84-98%.…”

Section: Diffusion Of Small Molecules Polymers Proteins and Cells Wmentioning

confidence: 99%

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Cryogels: Morphological, structural and adsorption characterisation

Gun'ko

Savina

Mikhalovsky

2013

Advances in Colloid and Interface Science

286

205

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*Graphical Abstract (for review)Cryotripic gelation technique allows the synthesis of solid and soft macroporous gels Textural characterisation of cryogel in native superhydrated state with noninvasive methods Adsorption and diffusion characteristics of macroporous cryogels with respect to macromolecules and cells Theoretical modelling of adsorption from aqueous media *Highlights (for review) Please find the revised manuscript entitled "Cryogels: morphological, structural and adsorption characterisation" by Vladimir M. Gun'ko, Irina N. Savina, Sergey V. Mikhalovsky to re-consider for publication in the "Advances in Colloid and Interface Science"The paper was completely edited and changed according to reviewers comments.Sincerely yours, Prof. V. M. Gun'koCover Letter ABSTRACTExperimental results on polymer, protein, and composite cryogels and data treatment methods used for morphological, textural, structural, adsorption and diffusion characterisation of the materials are analysed and compared. Treatment of microscopic images with specific software gives quantitative structural information on both native cryogels and freeze-dried materials that is useful to analyse the drying effects on their structure. A combination of cryoporometry, relaxometry, thermoporometry, small angle X-ray scattering (SAXS), equilibrium and kinetic adsorption of low and high-molecular weight compounds, diffusion breakthrough of macromolecules within macroporous cryogel membranes, studying interactions of cells with cryogels provides a consistent and comprehensive picture of textural, structural and adsorption properties of a variety of cryogels. This analysis allows us to establish certain regularities in the cryogel properties related to narrow (diameter 0.4 < d < 2 nm), middle (2 < d < 50 nm) and broad (50 < d < 100 nm) nanopores, micropores (100 nm < d < 100 m) and macropores (d > 100 m) with boundary sizes within modified life science pore classification. Particular attention is paid to water bound in cryogels in native superhydrated or freeze-dried states. At least, five states of water -free unbound, weakly bound (changes in the Gibbs free energy G < 0.5-0.8 kJ/mol) and strongly bound (G > 0.8 kJ/mol), and weakly associated (chemical shift of the proton resonance  H = 1-2 ppm) and strongly associated ( H = 3-6 ppm) waters can be distinguished in hydrated cryogels using 1 H NMR, DSC, TSDC, TG and other methods. Different software for image treatment or developed to analyse the data obtained with the adsorption, diffusion, SAXS, cryoporometry and thermoporometry methods and based on regularisation algorithms is analysed and used for the quantitative morphological, structural and adsorption characterisation of individual and composite cryogels, including polymers filled with solid nano-or microparticles.

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Section: Types Of Cryogel Based Composite and Hybrid Materialsmentioning

confidence: 99%

Section: Types Of Cryogel Based Composite and Hybrid Materialsmentioning

confidence: 99%

Section: Diffusion Of Small Molecules Polymers Proteins and Cells Wmentioning

confidence: 99%

See 1 more Smart Citation

Cryogels: Morphological, structural and adsorption characterisation

Gun'ko

Savina

Mikhalovsky

2013

Advances in Colloid and Interface Science

286

205

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“…The hydrogels were synthesized by sol−gel polymerization of titanium tetraisopropoxide using dialysis [6]. Silica cryogels have been synthesized with properties similar to those of silica aerogels, particularly in terms of particle morphology, density, porosity, and specific surface area [7]. These similarities can be explained by the high pressure produced by ice crystallites onto thin residual liquid films between these crystallites.…”

Section: Introductionmentioning

confidence: 99%

“…The resulting conditions are similar to the high-pressure conditions used to synthesize aerogels. The textural characterization of silica cryogels was based on nitrogen adsorption isotherms, scanning electron microscopy (SEM) images, structural analysis using infrared (FTIR) and nuclear magnetic resonance ( 29 Si MAS NMR) spectra [7]. Titania-silica hydrogels were molded into various shapes, microhoneycomb, self-standing bundle, microfibers, and powder, by a unidirectional freezing method [8].…”

Section: Introductionmentioning

confidence: 99%

High-pressure cryogelation of nanosilica and surface properties of cryosilicas

Gun’ko

Туров

Zarko

et al. 2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Gun'ko, V M.; Turov, V V.; Zarko, V I.; Prykhod'ko, G P.; Remez, O S.; Leboda, R; Skubiszewska-Zieba, J; Pahklov, E M.; and Blitz, Jonathan, "High-pressure cryogelation of nanosilica and surface properties of cryosilicas" (2013 AbstractSilica cryogels (cryosilicas) in a powder state were synthesized with different concentrations of fumed silica A-300 (C A-300 = 5-20 wt.%), sonicated in aqueous suspension, then frozen at 14 o C at different pressures in a high-pressure stainless steel reactor (a freezing bomb), and dried in air at room temperature. To analyze the effects of low temperature and high pressure, samples were also prepared at 14 o C or room temperature and standard pressure. The structural and adsorption properties of the powder materials were studied using nitrogen adsorption, highresolution transmission electron microscopy, infrared spectroscopy, thermogravimetry, lowtemperature 1 H NMR spectroscopy and thermally stimulated depolarization current. The structural, textural, adsorption and relaxation characteristics of high-pressure cryogel hydrogels and related dried powders are strongly dependent on the silica content in aqueous suspensions frozen at 1, 450 or 1000 atmospheres and then dried. The largest changes are found with C A-300 = 20 wt.% which are analyzed with respect to the interfacial behavior of nonpolar, weakly polar and polar adsorbates using low temperature 1 H NMR spectroscopy.

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