The dependence of the gelation time on the hydrolysis time in a two-step SiO2 sol-gel process

Boonstra, A.H.; Bernards, T.N.M.

doi:10.1016/0022-3093(88)90309-2

Cited by 92 publications

(35 citation statements)

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“…Such advantages are important to prepare single, massive and unchangeable glasses, thin films and optic fibers (1,2). Understanding the chemical reactions in the various steps of the sol-gel process leads to a better control of the process and therefore to an improvement in the reproducibility of the final product (3)(4)(5). The sol-gel technique also is an excellent method to prepare hybrid material.…”

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confidence: 99%

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

Barros

Almeida

Carvalho

et al. 2002

Braz J Med Biol Res

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We developed an efficient method to prepare a hybrid inorganicorganic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 µg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 µg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.

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mentioning

confidence: 99%

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

Barros

Almeida

Carvalho

et al. 2002

Braz J Med Biol Res

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“…All these measurements were carried out at the room temperature. 14,[16][17][18] and can be explained with the help of rates of hydrolysis-condensation reactions, as below. Near the point-of-zero-charge (PZC, where pH ≈2.5 for SiO 2 and its derivative), the condensation becomes rate limiting.…”

Section: Methodsmentioning

confidence: 99%

Influence of pH and Dye Concentration on the Physical Properties and Microstructure of New Coumarin 4 Doped SiO₂-PDMS ORMOSIL

2003

Bulletin of the Korean Chemical Society

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Physical properties and microstructure of new coumarin 4 doped SiO 2 -PDMS ORMOSILs, synthesized by one-step (OS, acid-catalysis) and two-step (TS, acid-base catalysis) routes of sol-gel method with varying pH (0.6 to 7) and dye content (5 × 10 −4 to 5 × 10 −2 mole), are reported. BET, UV-visible spectroscopy and SEM were used for characterizations. The increase in acid or base concentration increased the size of pores and aggregated silica particles. The samples with pH ≤ 2.5 were transparent and attributed to the small size of pores (~20 Å) and silica particles. The samples with pH > 2.5 were translucent or opaque due to non-uniform pore system formed by voids and large aggregated silica particles. The surface area was found a key factor controlling the interactions between the gel matrix and the dye. The OS samples with the highest dye concentration exhibited the minimal values of pore size, surface area and silica particle size, resulting in the concentration-quenching phenomenon.

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“…TMOS has a faster hydrolysis rate than TEOS [112]. The hydrolysis of TEOS needs an acidic or basic catalyst to occur, and the hydrolysis rate is in general directly proportional to the concentration of acid or base, except for when only small amounts of acids are present [113,114]. Hydrolysis and gelatation occur simultaneously.…”

Section: Hydrolysis and Condensationmentioning

confidence: 99%

Mesoporous Building Blocks: Synthesis and Characterization of Mesoporous Silica Particles and Films

Björk¹

2013

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On the cover, the structure of SBA-15 is illustrated. Inside the pores SEM micrographs have been inserted showing (clockwise from the top): rods, fibers, a film consisting of rods grown on a substrate, a film consisting of platelets grafted on a substrate, short rods, and platelets. In the center the sheet morphology is presented.© Emma Björk, unless otherwise stated.ISBN: 978-91-7519-516-2 ISSN: 0345-7524 Printed by LiU-tryck, Linköping, Sweden, 2013 Research is formalized curiosity. It is poking and prying with a purposeZora Neale Hurston (1903Hurston ( -1960 i ABSTRACTCatalyst supports, drug delivery systems, hosts for nanoparticles, and solar cells are just some examples of the wide range of exciting applications for mesoporous silica. In order to optimize the performance of a specific application, controlling the material's morphology and pore size is crucial. For example, short and separated particles are beneficial for drug delivery systems, while for molecular sieves, the pore size is the key parameter.In this thesis, mesoporous silica building blocks, crystallites, with hexagonally ordered cylindrical pores were synthesized, with the aim to understand how the synthesis parameters affect the particle morphology and pore size. The synthesis of the particles is performed using a sol-gel process, and in order to increase the pore size, a combination of low temperature, and additions of heptane and NH 4 F was used. By variations in the amounts of reagents, as well as other synthesis conditions, the particle morphology and pore size could be altered. Separated particles were also grown on or attached to substrates to form films. Also, a material with spherical pore structure was synthesized, for the first time using this method.It was found that a variation in the heptane concentration, in combination with a long stirring time, yields a transition between fiber and sheet morphologies. Both morphologies consist of crystallites, which for the fibers are joined end to end, while for the sheets they are attached side by side such that the pores are accessible from the sheet surface. The crystallites can be separated to a rod morphology by decreasing the stirring time and tuning the HCl concentration, and it was seen that these rods are formed within 5 min of static time, even though the pore size and unit cell parameters were evolving for another 30 min. Further studies of the effects of heptane showed that the shape and mesoscopic parameters of the rods are affected by the heptane concentration, up to a value where the micelles are fully saturated with heptane. It was also observed that the particle width increases with decreasing NH 4 F concentration, independent of heptane amount, and a platelet morphology can be formed. The formation time of the particles decrease with decreasing NH 4 F, and the growth mechanism for platelets was further studied. The pore sizes for various morphologies were altered by e.g. variations in the hydrothermal treatment conditions, or the method for removing the surfactants.ii T...

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The dependence of the gelation time on the hydrolysis time in a two-step SiO2 sol-gel process

Cited by 92 publications

References 10 publications

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

Influence of pH and Dye Concentration on the Physical Properties and Microstructure of New Coumarin 4 Doped SiO₂-PDMS ORMOSIL

Mesoporous Building Blocks: Synthesis and Characterization of Mesoporous Silica Particles and Films

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The dependence of the gelation time on the hydrolysis time in a two-step SiO2 sol-gel process

Cited by 92 publications

References 10 publications

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

Influence of pH and Dye Concentration on the Physical Properties and Microstructure of New Coumarin 4 Doped SiO2-PDMS ORMOSIL

Mesoporous Building Blocks: Synthesis and Characterization of Mesoporous Silica Particles and Films

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Influence of pH and Dye Concentration on the Physical Properties and Microstructure of New Coumarin 4 Doped SiO₂-PDMS ORMOSIL