Fabrication of Anisotropic Porous Silica Monoliths by Means of Magnetically Controlled Phase Separation in Sol–Gel Processes

This work reports a facile and inexpensive preparation of porous silica monolithsviaanin situsol–gel method using potassium silicate precursors in the presence of porosity controlling and drying regulatory additives.

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Bimodal porous silica monoliths obtained by phase separation in non-aqueous media

Journal of Materials Chemistry ◽

10.1039/b918412k ◽

2010 ◽

Vol 20 (5) ◽

pp. 964-971 ◽

Cited By ~ 21

Author(s):

Jean Le Bideau ◽

M. Yusuf Miah ◽

André Vioux ◽

François Fajula ◽

Anne Galarneau

Keyword(s):

Phase Separation ◽

Aqueous Media ◽

Porous Silica ◽

Silica Monoliths

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Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170967 ◽

1994 ◽

Vol 52 ◽

pp. 646-647

Author(s):

J. Tong ◽

L. Eyring

Keyword(s):

Fracture Toughness ◽

Phase Separation ◽

Sol Gel ◽

Great Influence ◽

High Strength ◽

Chemical Durability ◽

Separation Method ◽

Toughening Mechanism ◽

Ceramic Films ◽

Zirconia Toughened Alumina

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

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Porous Gel Coatings Obtained by Phase Separation in ORMOSIL System

MRS Proceedings ◽

10.1557/proc-628-cc7.6 ◽

2000 ◽

Vol 628 ◽

Cited By ~ 1

Author(s):

Kazuki Nakanishi ◽

Souichi Kumon ◽

Kazuyuki Hirao ◽

Hiroshi Jinnai

Keyword(s):

Phase Separation ◽

Reaction Time ◽

Volume Fraction ◽

Sol Gel ◽

Reaction Times ◽

Dip Coating ◽

Coating Solution ◽

Coating Method ◽

Gel Phase ◽

Dip Coating Method

ABSTRACTMacroporous silicate thick films were prepared by a sol-gel dip-coating method accompanied by the phase separation using methyl-trimethoxysilane (MTMS), nitric acid and dimethylformamide (DMF) as starting components. The morphology of the film varied to a large extent depending on the time elapsed after the hydrolysis until the dipping of the coating solution. On a glass substrate, the films prepared by early dipping had inhomogeneous submicrometer-sized pores on the surface of the film. At increased reaction times, relatively narrow sized isolated macropores were observed and their size gradually decreased with the increase of reaction time. On a polyester substrate, in contrast, micrometer-sized isolated spherical gel domains were homogeneously deposited by earlier dippings. With an increase of reaction time, the volume fraction of the gel phase increased, then the morphology of the coating transformed into co-continuous gel domains and macropores, and finally inverted into the continuous gel domains with isolated macropores. The overall morphological variation with the reaction time was explained in terms of the phase separation and the structure freezing by the forced gelation, both of which were induced by the evaporation of methanol during the dipping operation.

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Development of Novel Oral Formulations of Disulfide Antioxidants Based on Porous Silica for Controlled Release of the Drugs

Materials ◽

10.3390/ma14040963 ◽

2021 ◽

Vol 14 (4) ◽

pp. 963

Author(s):

Ekaterina S. Dolinina ◽

Elena V. Parfenyuk

Keyword(s):

Antioxidant Activity ◽

Surface Chemistry ◽

Sol Gel ◽

Porous Silica ◽

The Body ◽

Oral Drug ◽

Therapeutic Concentration ◽

Release Process ◽

Zero Order Kinetics ◽

Long Time

Powerful antioxidant α-lipoic acid (LA) exhibits limited therapeutic efficiency due to its pharmacokinetic properties. Therefore, the purpose of this work was to evaluate the ability of silica-based composites of LA as well as its amide (lipoamide, LM), as new oral drug formulations, to control their release and maintain their therapeutic concentration and antioxidant activity in the body over a long time. The composites synthesized at different sol–gel synthesis pH and based on silica matrixes with various surface chemistry were investigated. The release behavior of the composites in media mimicking pH of digestive fluids (pH 1.6, 6.8, and 7.4) was revealed. The effects of chemical structure of the antioxidants, synthesis pH, surface chemistry of the silica matrixes in the composites as well as the pH of release medium on kinetic parameters of the drug release and mechanisms of the process were discussed. The comparative analysis of the obtained data allowed the determination of the most promising composites. Using these composites, modeling of the release process of the antioxidants in accordance with transit conditions of the drugs in stomach, proximal, and distal parts of small intestine and colon was carried out. The composites exhibited the release close to the zero order kinetics and maintained the therapeutic concentration of the drugs and antioxidant effect in all parts of the intestine for up to 24 h. The obtained results showed that encapsulation of LA and LM in the silica matrixes is a promising way to improve their bioavailability and antioxidant activity.

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Eco-fabrication of hierarchical porous silica monoliths by ice-templating of rice husk ash

Green Chemistry ◽

10.1039/c6gc02153k ◽

2017 ◽

Vol 19 (1) ◽

pp. 188-195 ◽

Cited By ~ 32

Author(s):

Amin Bahrami ◽

Ulla Simon ◽

Niloofar Soltani ◽

Sara Zavareh ◽

Johannes Schmidt ◽

...

Keyword(s):

Rice Husk ◽

Rice Husk Ash ◽

Porous Silica ◽

Synthesis Process ◽

Sustainable Chemistry ◽

Silica Monoliths ◽

Hierarchical Porous ◽

Ice Templating

In this study, within a sustainable chemistry approach, a clean and eco-friendly synthesis process of silica monoliths compatible with environmental limitations is developed.

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Bioencapsulation in Sol-Gel Glasses

MRS Proceedings ◽

10.1557/proc-519-171 ◽

1998 ◽

Vol 519 ◽

Cited By ~ 9

Author(s):

L. Bergogne ◽

S. Fennouh ◽

J. Livage ◽

C. Roux

Keyword(s):

Sol Gel ◽

Porous Silica ◽

Silica Matrix ◽

Whole Cells ◽

The Past ◽

Wide Range ◽

Activity Of Enzymes ◽

Gel Glasses ◽

Micro Organisms

AbstractBioencapsulation in sol-gel materials has been widely studied during the past decade. Trapped species appear to retain their bioactivity in the porous silica matrix. Small analytes can diffuse through the pores allowing bioreactions to be performed in-situ, inside the sol-gel glass. A wide range of biomolecules and micro-organisms have been encapsulated. The catalytic activity of enzymes is used for the realization of biosensors or bioreactors. Antibody-antigen recognition has been shown to be feasible within sol-gel matrices. Trapped antibodies bind specifically the corresponding haptens and can be used for the detection of traces of chemicals. Even whole cells are now encapsulated without any alteration of their cellular organization. They can be used for the production of chemicals or as antigens for immunoassays.

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Sol-Gel Derived Silica Layers for Low-k Dielectrics Applications

MRS Proceedings ◽

10.1557/proc-612-d5.26.1 ◽

2000 ◽

Vol 612 ◽

Cited By ~ 4

Author(s):

Sylvie Acosta ◽

André Ayral ◽

Christian Guizard ◽

Charles Lecornec ◽

Gérard Passemard ◽

...

Keyword(s):

Average Pore Size ◽

Sol Gel ◽

Porous Silica ◽

Thin Layers ◽

Gaseous Ammonia ◽

Potential Candidate ◽

Average Pore ◽

Synthesis Strategy ◽

Silica Layers ◽

Highly Porous

AbstractPorous silica exhibits attractive dielectric properties, which make it a potential candidate for use as insulator into interconnect structures. A new way of preparation of highly porous silica layers by the sol-gel route was investigated and is presented. The synthesis strategy was based on the use of common and low toxicity reagents and on the development of a simple process without gaseous ammonia post-treatment or supercritical drying step. Defect free layers were deposited by spin coating on 200 mm silicon wafers and characterized. Thin layers with a total porosity larger than 70% and an average pore size of 5 nm were produced. The dielectric constant measured under nitrogen flow on these highly porous layers is equal to ∼ 2.5, which can be compared to the value calculated from the measured porosity, ∼ 1.9. This difference is explained by the presence of water adsorbed on the hydrophilic surface of the unmodified silica.

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