Pore structure evolution in silica gel during aging/drying. III. Effects of surface tension

Deshpande, Ravindra; Hua, Duen-Wu; Smith, Douglas M.; Brinker, C. Jeffrey

doi:10.1016/s0022-3093(05)80380-1

Cited by 155 publications

(54 citation statements)

References 8 publications

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“…1. The chemical surface modification of the hydrogels by nonpolar alkyl/aryl groups is an indispensable step before the APD, prohibiting the formation of new siloxane bonds between the adjacent silica cluster and thereby preventing irreversible shrinkage of the gel [41,42]. In the present work, the surface of the sodium silicatebased hydrogels was organically modified by tri-methyl groups present in trimethylchlorosilane by simultaneous solvent exchange and surface modification process.…”

Section: Mechanisms Of Simultaneous Solvent Exchange and Surface Modimentioning

confidence: 98%

Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure

Sarawade

Kim

Hilonga

et al. 2010

Korean J. Chem. Eng.

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The experimental results of aging time and temperature on the textural properties of water-glass (sodium silicate)-based silica aerogels are reported and discussed. Aging of the hydrogel for different times and temperatures led to an ability to increase the stiffness and strength of the networks. These improvements enabled the gel to withstand ambient pressure drying (APD) and, consequently, preserve the highly porous silica network without collapse. The pore size and volume increased with increasing aging temperature and time, while the specific surface area decreased. Monolithic aerogels with extremely low bulk density (~0.069 g/cm 3 ), high specific surface area (820 m 2 g −1 ), large cumulative pore volume (3.8 cm 3 g −1 ), and high porosity (~96%) were obtained by aging at 60 o C for 18 hours. Therefore, easy synthesis of monolithic silica aerogels at ambient pressure is achievable using a relatively inexpensive silica precursor (sodium silicate).

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Section: Mechanisms Of Simultaneous Solvent Exchange and Surface Modimentioning

confidence: 98%

Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure

Sarawade

Kim

Hilonga

et al. 2010

Korean J. Chem. Eng.

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“…Prior to the physical characterizations described in Sections 2.5 and 2.6, the gels were dried at ambient temperature in a manner that minimizes shrinkage due to collapse of the pores [36,37]. Multi-step solvent exchange was undertaken with nonpolar solvents to avoid the capillary action associated with drying and shrinkage [38,39].…”

Section: Aerogel Preparationmentioning

confidence: 99%

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

et al. 2008

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Organically-modified siloxanes were used as host materials to examine the influence of surface chemistry on protein conformation in a crowded environment. The sol-gel materials were prepared from tetramethoxysilane and a series of monosubstituted alkoxysilanes, RSi(OR′) 3 , featuring alkyl groups of increasing chain length in the R-position. Using circular dichroism spectroscopy in the far-UV region, apomyoglobin was found to transit from an unfolded state to a native-like helical state as the content of the hydrophobic precursor increased from 0-15%. At a fixed molar content of 5% RSi(OR') 3 , the helical structure of apomyoglobin increased with the chain length of the R-group, i.e. methyl < ethyl < n-propyl < n-butyl < n-hexyl. This trend also was observed for the tertiary structure of ribonuclease A, suggesting that protein folding and biological activity are sensitive to the hydrophilic/hydrophobic balance of neighboring surfaces. The observed changes in protein structure did not correlate with total surface area or the average pore size of the modified glasses, but scanning electron microscopy images revealed an interesting relationship between surface morphology and alkyl chain length. The unexpected benefit of incorporating a low content of hydrophobic groups into a hydrophilic surface may lead to materials with improved biocompatibility for use in biosensors and implanted devices.

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“…The effect of pore fluid can be seen in the study of Deshpande et al 17 , who have shown that, for aprotic pore fluids that do not react chemically with the gel network, increasing the pore fluid surface tension causes a general trend of reduction in pore volume and pore size, consistent with expectations of Eqs. 4 and 5.…”

Section: Management Of Capillary Pressuresupporting

confidence: 67%

Sol-Gel Processing of Amorphous Nanoporous Silicas: Thin Films and Bulk

Brinker

Wallace

Raman

et al.

Fundamental Materials Research

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Pore structure evolution in silica gel during aging/drying. III. Effects of surface tension

Cited by 155 publications

References 8 publications

Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure

Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

Sol-Gel Processing of Amorphous Nanoporous Silicas: Thin Films and Bulk

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