Reactive modeling of the initial stages of alkoxysilane polycondensation: effects of precursor molecule structure and solution composition

Deetz, Joshua D.; Faller, Roland

doi:10.1039/c5sm00964b

Cited by 21 publications

(20 citation statements)

References 54 publications

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“…The smaller size of the hydroxyl groups in comparison with bulkier methoxy groups, as ligands on the silanes, enables easier accessibility for condensation with the surface. 23 Despite the accelerated kinetics of DTHS in comparison to DTMS, the formed monolayers show similar morphological characteristics, such as surface roughness, in-plane molecular area, tilt angle, and radius of gyration. This indicates that the alkoxylation of the substrate had little effect on the properties of the formed monolayer.…”

Section: Discussionmentioning

confidence: 99%

“…The methoxy groups are bulkier and may hinder condensation. Past studies 18,23 have indicated that bulky alkoxysilane groups hinder hydrolysis and condensation. Another possible explanation for the enhanced kinetics of silanization is the lack of surface bound methoxysilane groups.…”

Section: Effects Of Hydrolyzation Of Silane Moleculementioning

confidence: 99%

“…The chemisorption of silanes to silica substrates occurs through condensation with hydrolyzed silicons 21 and strained siloxane rings 22 on the surface. Reactive force fields for molecular dynamics simulations have recently been developed 23 which are capable of modeling the condensation of alkoxysilanes to a silica substrate.…”

Section: Introductionmentioning

confidence: 99%

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Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

2016

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Abstract:We perform reactive molecular dynamics simulations of monolayer formation by silanes on hydroxylated silica substrates. Solutions composed of alkylmethoxysilanes or alkylhydroxysilanes in hexane are placed in contact with a hydroxylated silica surface and simulated using a reactive force field (ReaxFF). In particular, we have modeled the deposition of butyl-, octyl-, and dodecyltrimethoxysilane to observe the dependence of alkylsilyl chain length on monolayer formation. We additionally modeled silanization using dodecyltrihydroxysilane, which allows for the comparison of two grafting mechanisms of alkoxysilanes: (1) direct condensation of alkoxysilane with surface bound silanols, and (2) a two-step hydrolysiscondensation mechanism. In order to emulate an infinite reservoir of reactive solution far away from the substrate, we have developed a method in which new precursor molecules are periodically added to a region of the simulation box located away from the surface. It is determined that the contact angle of alkyl tails bound to the surface is dependent on their grafting density. During the early stages of grafting alkoxy-and hydroxysilanes to the substrate, a preference is shown for silanes to condense with silanols further from the substrate surface, and also nearby to neighboring surface-bound silanols. The kinetics of silica silanization by hydroxysilanes were observed to be much faster than methoxysilanes. However, the as-deposited hydroxysilane monolayers show similar morphological characteristics as those formed by methoxysilanes.

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Section: Discussionmentioning

confidence: 99%

Section: Effects Of Hydrolyzation Of Silane Moleculementioning

confidence: 99%

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Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

2016

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“…Figure a illustrates the reaction procedure for QDs-SiO 2 -BNAs. In a typical reaction, QDs-SiO 2 particles were prepared according to a classical method. , BN nanoplates were surface-treated by silica encapsulation via a hydrolysis polycondensation reaction of tetramethoxysilane (TMOS) in ethanol. Subsequently, the QDs-SiO 2 -BNAs particles were prepared by simply mixing the QDs-SiO 2 particles with the BN-SiO 2 particles in ethanol solution in the presence of a slight amount of TMOS.…”

Section: Resultsmentioning

confidence: 99%

Highly Efficient and Thermally Stable QD-LEDs Based on Quantum Dots-SiO₂-BN Nanoplate Assemblies

Xie

Yang

Zhang

et al. 2019

ACS Appl. Mater. Interfaces

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Silica encapsulation effectively elevates the resistance of quantum dots (QDs) against water and oxygen. However, QDs-SiO 2 composites present low thermal conductivity and strong thermal accumulation, leading to considerable fluorescence quenching of QDs in optoelectronic devices at high power. Here, a sandwich structural QDs-SiO 2 -BN nanoplate assembly material (QDs-SiO 2 -BNAs) is developed to reduce the thermal quenching and enhance the stability of QDs in LEDs. The QDs-SiO 2 -BNAs is fabricated by embedding QDs-SiO 2 into the interlayer of layer-by-layer assembled BN nanoplates, and the BN nanoplates are pretreated by SiO 2 encapsulation to strengthen the interaction with QDs-SiO 2 . This assembly structure endows the QDs with fast heat dissipation and double surface protection against air. The medium power QDs-converted LEDs (QD-LEDs) fabricated by direct on-chip packaging of the QDs-SiO 2 -BNAs gain 44.2 °C temperature reduction at 0.5 W in comparison with conventional QD-LEDs. After aging, the resulting QD-LEDs present degradation of only 1.2% under sustained driving for 250 h. The QD-LEDs also pass the 1 week reliability test at 85 °C/85% RH with <±0.01 shift of the color coordinates, demonstrating the profound potential of the QDs-SiO 2 -BNAs in LED lighting and display applications.

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“…Silane alkoxy groups are first to be introduced onto polyolefin backbone by peroxideinitiated grafting of unsaturated silane, then transformed to siloxane ( Si O Si ) through catalytically hydrolytic condensation using water or moisture (Scheme 1). [5] Compared with the other two methods, silanecrosslinking has advantages of low capital investment and favorable properties of the processed materials. [6] In the case of polypropylene (PP), predominant macro-radical fragmentation during radiation and peroxide modification [7] means silane grafting and moisture crosslinking have a greater advantage in the production of crosslinked PP.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of crosslinking in benzoyl peroxide‐initiated functionalization of vinyltriethoxysilane onto polypropylene in the water medium

Yuan

Shao

Liang

et al. 2020

J of Applied Polymer Sci

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Silane grafting and moisture crosslinking is one of the most common methods in the production of crosslinked polyolefin. A remarkable increase in the percentage of gel in the product was observed in benzoyl peroxide‐mediated aqueous suspension grafting of vinyltriethoxysilane onto polypropylene. Aimed to explore the crosslinking reaction mechanism in this functionalization process, comprehensive experiments had been conducted and the grafted products were characterized by mass spectrometry, 1H NMR, and 29Si NMR spectroscopy. Finally, a novel crosslinking mechanism was proposed based on the characterization results.

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Reactive modeling of the initial stages of alkoxysilane polycondensation: effects of precursor molecule structure and solution composition

Abstract: Reactive molecular dynamics simulations are used to model polycondensation of alkoxysilanes in solution. Different precursor monomers are compared and steric effects on polycondensation kinetics are observed. The impact of the alcohol and water composition in solution are explored.

Cited by 21 publications

References 54 publications

Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

Highly Efficient and Thermally Stable QD-LEDs Based on Quantum Dots-SiO₂-BN Nanoplate Assemblies

Mechanism of crosslinking in benzoyl peroxide‐initiated functionalization of vinyltriethoxysilane onto polypropylene in the water medium

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Reactive modeling of the initial stages of alkoxysilane polycondensation: effects of precursor molecule structure and solution composition

Abstract: Reactive molecular dynamics simulations are used to model polycondensation of alkoxysilanes in solution. Different precursor monomers are compared and steric effects on polycondensation kinetics are observed. The impact of the alcohol and water composition in solution are explored.

Cited by 21 publications

References 54 publications

Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

Highly Efficient and Thermally Stable QD-LEDs Based on Quantum Dots-SiO2-BN Nanoplate Assemblies

Mechanism of crosslinking in benzoyl peroxide‐initiated functionalization of vinyltriethoxysilane onto polypropylene in the water medium

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Product

Resources

About

Highly Efficient and Thermally Stable QD-LEDs Based on Quantum Dots-SiO₂-BN Nanoplate Assemblies