M<scp>ECHANISMS AND</scp> K<scp>INETICS OF</scp> S<scp>ELF</scp>-A<scp>SSEMBLED</scp> M<scp>ONOLAYER</scp> F<scp>ORMATION</scp>

Schwartz, Daniel K.

doi:10.1146/annurev.physchem.52.1.107

Cited by 654 publications

(491 citation statements)

References 76 publications

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“…The surface roughness decreases as more silanes are grafted to the interface. This agrees with the results of atomic force microscopy measurements 49,50 . As was shown with the alkoxysilanes in the previous section, the silanes initially graft to locations above the average axial position of silanols on the surface.…”

Section: Effects Of Hydrolyzation Of Silane Moleculesupporting

confidence: 92%

“…This is also seen in atomic force microscopy experiments for silanization of silica surfaces 49,50 . As the coverage of the silica surface increases, the surface roughness decreases.…”

Section: Effects Of Alkylsilyl Headgroup Size and Grafting Density Onsupporting

confidence: 52%

“…Both, radius of gyration and monolayer thickness increase with headgroup size. 49 Alkoxy groups are formed on the substrate which we believe hinder the kinetics of silanization of methoxysilanes under neutral conditions, by reacting with silanol groups. The reaction with silanols is likely a consequence of using anhydrous, neutral pH, and high temperature conditions for our simulations, as silica has been shown elsewhere to be alkoxylated under these conditions.…”

Section: Discussionmentioning

confidence: 99%

“…This resembles a disordered monolayer at the interface. Previous studies have indicated the formation of rough island structures 1,49 , which transition into smooth layers once full coverage is achieved. Such island domains are not observed here.…”

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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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: Effects Of Hydrolyzation Of Silane Moleculesupporting

confidence: 92%

“…This is also seen in atomic force microscopy experiments for silanization of silica surfaces 49,50 . As the coverage of the silica surface increases, the surface roughness decreases.…”

Section: Effects Of Alkylsilyl Headgroup Size and Grafting Density Onsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Section: Effects Of Hydrolyzation Of Silane Moleculementioning

confidence: 99%

See 2 more Smart Citations

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

2016

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“…Under such conditions, crystallization depends on the surface density of macromolecules, in addition to their chemical functionality and conformation. For instance, in the case of self-assembled monolayers (SAMs), the surface density of attached molecules determines the conformational ensemble being random, partially-disordered or ordered and close-packed (Schwartz 2001). This in turn can affect heterogeneous nucleation and crystal growth.…”

Section: Mineralization and Crowding In Quasi-2 Dimensionsmentioning

confidence: 99%

Mineralization and non-ideality: on nature’s foundry

Rao¹,

Cölfen

2016

Biophys Rev

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Understanding how ions, ion-clusters and particles behave in non-ideal environments is a fundamental question concerning planetary to atomic scales. For biomineralization phenomena wherein diverse inorganic and organic ingredients are present in biological media, attributing biomaterial composition and structure to the chemistry of singular additives may not provide a holistic view of the underlying mechanisms. Therefore, in this review, we specifically address the consequences of physico-chemical non-ideality on mineral formation. Influences of different forms of non-ideality such as macromolecular crowding, confinement and liquid-like organic phases on mineral nucleation and crystallization in biological environments are presented. Novel prospects for the additive-controlled nucleation and crystallization are accessible from this biophysical view. In this manner, we show that non-ideal conditions significantly affect the form, structure and composition of biogenic and biomimetic minerals.

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