Parallel Optimization of a Reactive Force Field for Polycondensation of Alkoxysilanes

Deetz, Joshua D.; Faller, Roland

doi:10.1021/jp504138r

Cited by 39 publications

(51 citation statements)

References 76 publications

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“…Our recently developed force field 29 has been applied to observe the early stages of monolayer formation. A hydroxylated silica substrate was exposed to a solution containing hexane and silane (butyl-, octyl-, dodecyl-trimethoxysilane, or dodecyl-trihydroxysilane).…”

Section: Discussionmentioning

confidence: 99%

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%

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

2016

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“…[29][30][31] By the oxidation-reduction recycles, the ceria could inhibit the degradation resulted from mechanism II continuously. 33,34 There were plenty of hydroxyl groups on the surface of CeO 2 particles. Figure 7 shows the surface modification mechanism.…”

Section: The Antioxidant Property Of Ceriamentioning

confidence: 99%

“…Figure 7 shows the surface modification mechanism. 33,34 There were plenty of hydroxyl groups on the surface of CeO 2 particles. After the hydrolysis of SiAOCH 3 , the resulting silanol groups would dehydrate with hydroxyl groups of CeO 2 particles.…”

Section: The Antioxidant Property Of Ceriamentioning

confidence: 99%

The effect of ceria nanoparticles on improving heat resistant properties of fluorosilicone rubber

Liu

Chen

et al. 2016

J of Applied Polymer Sci

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The thermal aging behavior of poly(3,3,3-trifluoropropyl)methylsiloxane was investigated by thermal gravimetric analysis and isothermal aging tests, and the results indicated the degradation mechanism II, oxidation scission of the side groups, played a more important role when the temperature was below 350 8C. The addition of ceria had significantly improved the thermal stability of fluorosilicone rubber (FSR) by inhibiting the oxidation scission. Moreover, two types of ceria including laminar-structure ceria (LS-CeO 2 ) and nanoparticle ceria (N-CeO 2 ) were prepared and surface was modified by KH570 and characterized by scanning electron microscopy, transmission electron microscope, and X-ray diffractometer. FSR incorporated with modified LS-CeO 2 and N-CeO 2 revealed a significant improvement on the heat resistant properties. In particular, after having been thermal oxidative aged for 70 h at 250 8C, FSR containing 2 wt % of modified N-CeO 2 maintained 72.6% of tensile strength and 63.9% of elongation at break, respectively, while FSR without ceria completely failed.

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“…The additional memory use significantly reduces duration of one step. 9. Check whether X l+1 is already in the list.…”

Section: Parallelization Of the Mgsamentioning

confidence: 99%

Multifactorial global search algorithm in the problem of optimizing a reactive force field

2016

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We present a new multifactorial global search algorithm (MGSA) and check the operability of the algorithm on the Michalewicz and Rastrigin functions. We discuss the choice of an objective function and additional search criteria in the context of the problem of reactive force field (ReaxFF) optimization and study the ranking of the ReaxFF parameters together with their impact on the objective function.

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Parallel Optimization of a Reactive Force Field for Polycondensation of Alkoxysilanes

Cited by 39 publications

References 76 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

The effect of ceria nanoparticles on improving heat resistant properties of fluorosilicone rubber

Multifactorial global search algorithm in the problem of optimizing a reactive force field

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