Infrared Spectroscopy of Silica Sols–Effects of Water Concentration, Catalyst, and Aging

Chu, Peir; Clark, David E.

doi:10.1080/00387019208020687

Cited by 35 publications

(23 citation statements)

References 12 publications

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“…En este peque-o tiempo de reacci-n se produce la disminuci-n brusca de las bandas correspondientes a las vibraciones de tensi-n asimŽtrica y simŽtrica del enlace Si-O-C situadas a 1170 y 1080 cm -1 (14,15), visualiz ‡ndose en esta regi-n (1200-1000 cm -1 ) oenicamente las bandas de tensi-n asimŽtrica y simŽtrica respectivamente del enlace C-O de etanol e isopropanol (16,17). La desaparici-n casi en su totalidad de las bandas de vibraci-n Si-O-C y la presencia de las bandas del etanol , a 1090, 1050 y 880 cm -1 indican que en este corto per'odo de tiempo se ha producido la reacci-n de hidr-lisis del TEOS.…”

Section: 1-hidr-lisis Y Autocondensaci-n Del Teos En Ausencia De Punclassified

Estudio por espectroscopía infrarroja de la reacción de hidrólisis y policondensación del IEOS en presencia de PDMS

Velasco¹,

Rubio²,

Oteo³

2001

Bol. Soc. Esp. Ceram. Vidr.

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En este trabajo se ha estudiado mediante Espectroscop'a Infrarroja por transformada de Fourier la influencia del peso molecular de pol'meros org ‡nicos (PDMS) en la velocidad de hidr-lisis y policondensaci-n de Tetraetilortosilicato (TEOS) en medio acuoso ‡cido. La evoluci-n de las bandas situadas a 880, 1180 y 850 cm -1 permite estudiar los procesos de hidr-lisis, autocondensaci-n y copolimerizaci-n respectivamente. La velocidad de hidr-lisis y la autocondensaci-n de TEOS no se afecta por la presencia de pol'mero. Sin embargo la reacci-n de copolimerizaci-n TEOS-PDMS disminuye al aumentar el peso molecular del pol'mero lo que es debido a diferencias en la concentraci-n de grupos -OH de final de cadena del pol'mero y a la viscosidad de dichos pol'meros. Los materiales obtenidos a partir de PDMS de alto peso molecular (18000 y 26000 g/mol) presentan tiempos de gelificaci-n an ‡logos al TEOS hidrolizado, mientras que los tiempos de gelificaci-n disminuyen cuando se emplean polimeros de menor peso molecular (550 y 1700 g/mol). Este trabajo muestra que la Espectroscop'a Infrarroja es una buena tŽcnica para el seguimiento de las reacciones que ocurren en el proceso sol-gel. Palabras clave: Ormosil, TEOS, PDMS, hidr-lisis, policondensaci-n, FT-IR. Study by FT-IR Spectroscopy of the reaction of hydrolysis and polycondensation of TEOS in presence of PDMS.In this work, we have studied, by FT-IR Spectroscopy, the influence of the molecular weight of organic polymers (polydimethylsiloxane, PDMS) in the hydrolysis and polycondensation reactions of tetraethylortosilicate (TEOS) in acid medium. Following of the bands located at 880, 1180 and 850 cm -1 , the hydrolysis and selfcondensation of TEOS process and copolymerization between TEOS and PDMS respectively can be studied. The rates of hydrolysis and self-condensation of TEOS are not affected by the presence of the polymer. However , the reaction of copolymerization between TEOS and PDMS decreases when the molecular weight of polymer increase, and this is due to both the diferences in the concentration of silanol end groups of polymer and polymer viscosity. The materials obtained from high molecular weight (18000 and 26000 g/mol) have gelification times as TEOS. On the other hand the gelification time decreases when polymers of lower molecular weight ( 550 and 1700 g/mol) are used. This work shows that FT-IR Spectroscopy can be applied to investigate the sol-gel reactions. KEY words: Ormosil, TEOS, PDMS, hydrolysis, polycondensation, FT-IR 1.-INTRODUCCIîNEl desarrollo de los materiales h'bridos org ‡nico-inorg ‡nico est ‡ basado fundamentalmente en la incorporaci-n de especies oligomŽricas y polimŽricas con grupos funcionales apropiados en una red inorg ‡nica constituida fundamentalmente de enlaces Si-O-Si. Dado que, la dispersi-n de s'lice a nivel molecular es imposible, es necesario la utilizaci-n de precursores (tetraalcoxisilanos) que generen Òin situÓ la red inorg ‡nica mediante reacciones de hidr-lisis y policondensaci-n dentro de pol'meros org ‡nicos solubles (1,2). ...

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Section: 1-hidr-lisis Y Autocondensaci-n Del Teos En Ausencia De Punclassified

Estudio por espectroscopía infrarroja de la reacción de hidrólisis y policondensación del IEOS en presencia de PDMS

Velasco¹,

Rubio²,

Oteo³

2001

Bol. Soc. Esp. Ceram. Vidr.

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“…Then, propylene oxide, a kind of proton scavenger, was added to the above mixture to increase the pH of system higher than 4.0 by reacting with the protons accompanying with an irreversible ring-opening reaction to generate 1-chloro-2-propanol and 2-chloro-1-propanol (reaction (5)) [33]. In this case, the generation of SiO 2 from the condensation of Si(OH) 4 will be facilitated by increasing the sol-gel pH value (as described in reaction (3) and (4)) [28][29][30][31][32]. With this two-step sol-gel method, the hydrolysis and condensation rates would be significantly increased.…”

Section: Preparation Of LI 2 Mnsio 4 and Li 2 Mnsio 4 /Cmentioning

confidence: 95%

“…In this stage, a jelly-like pink gel was generated. The generation of the SiO 2 gel was facilitated effectively due to the increasing of the pH value caused by the proton-consuming reaction of propylene oxide ring-opening (as described in reaction (3)) [28][29][30][31][32]. The ICP-AES results described in Section 2.2 show that the relative ratios were 99.9% Si and 0.1% Mn, hence, the gel was SiO 2 gel and Mn appeared as a kind of water-soluble substances.…”

Section: Preparation Of LI 2 Mnsio 4 and Li 2 Mnsio 4 /Cmentioning

confidence: 99%

“…In this step, the hydrolysis proceeds much faster than condensation [28][29][30][31][32]. The TEOS was almost completely hydrolyzed to Si(OH) 4 in a few minutes in a high excess water (H 2 O/TEOS = 14.8) and acid medium, and the significant condensation is prevented [28][29][30][31][32].…”

Section: Preparation Of LI 2 Mnsio 4 and Li 2 Mnsio 4 /Cmentioning

confidence: 99%

“…In the first step, the hydrolysis of TEOS to silanols is accelerated in an acidic environment (such as the pH value range of 0-3) by adding hydrochloric acid [28][29][30][31][32]. In the second step, the alkaline, such as ammonia, is added to the solution to raise the pH value to accelerate the condensation of the silanols [28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

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Developing artificial protective layers is an effective strategy to address the issue of dendrites for aqueous Zn‐metal batteries (ZMBS). However, drawbacks such as rough microscopic morphology, excessive thickness, and single functionality remain, limiting the attainment of a stable zinc anode. Herein, a novel multifunctional organic–inorganic hybrid artificial protective layer is produced by splicing inorganic fragments onto organic materials in situ using a chemical sewing. The protective layer is well‐compatible and also retains the function of organic and inorganic materials, which not only inhibits dendrite production but also alleviates Zn corrosion. The Si─OH bond of the zincophilic group enables planar Zn deposition while forming hydrogen bonds with water, suppressing water activity near the anode and reducing the hydrogen evolution reaction. As expected, the Zn||Zn symmetric cell with a protective layer provides high cycling stability of more than 1960 h at 1 mA cm−2, which is about 28 times higher than that of the symmetric cell assembled without the protective layer. More importantly, a Zn||V2O5 full cell with an ultra‐long lifetime has been achieved with an artificial protective layer. This work provides a potential viable path to achieve long‐lived ZMBS.

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Infrared Spectroscopy of Silica Sols–Effects of Water Concentration, Catalyst, and Aging

Cited by 35 publications

References 12 publications

Estudio por espectroscopía infrarroja de la reacción de hidrólisis y policondensación del IEOS en presencia de PDMS

Estudio por espectroscopía infrarroja de la reacción de hidrólisis y policondensación del IEOS en presencia de PDMS

Fast sol–gel synthesis of mesoporous Li2MnSiO4/C nanocomposite with improved electrochemical performance for lithium-ion batteries

A Chemical Sewing Enabled All‐In‐One Control Interface for Robust Zinc Metal Anodes

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