Molecular dynamics simulation study of growth regimes during polycondensation of silicic acid: From silica nanoparticles to porous gels

Sudin Bhattacharya, John Kieffer

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Abstract

Molecular dynamics simulations based on a reactive force field with charge transfer were used to model the sol-gel synthesis of nanoporous silica gels in an aqueous environment. Three distinct growth regimes emerge, depending on the solvent-to-silica ratio: compact nanoparticles, percolated silica networks, and branched clusters. These growth regimes can be identified on the basis of distinctive structural features. In the case of compact particles, the radial distribution functions exhibit a broad maximum that coincides with the radius of gyration of the aggregates, whereas in continuous networks the radial distribution function increases steadily beyond the near-range structural features. Furthermore, these growth regimes can be distinguished on the basis of the concentrations of structural defects, such as dangling bonds and residual OH groups. The growth kinetics of individual regimes are characterized by different relative contributions of atomic diffusion to the overall aggregation rate. Finally, the resulting gel structures possess different mechanical stability, as can be assessed by quantifying the extents of structural collapse during simulated supercritical drying.

Original languageEnglish (US)
Pages (from-to)1764-1771
Number of pages8
JournalJournal of Physical Chemistry C
Volume112
Issue number6
DOIs
StatePublished - Feb 14 2008
Externally publishedYes

Profile

Erythrasma
Silica
gels
silicon dioxide
Nerve Crush
Auditory Pathways
Myosins
Cholesterol
Distribution functions
Molecular dynamics
Gels
Nanoparticles
Computer simulation
radial distribution
distribution functions
molecular dynamics
nanoparticles
simulation
Amino Acid Oxidoreductases
Feline Sarcoma Viruses

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

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abstract = "Molecular dynamics simulations based on a reactive force field with charge transfer were used to model the sol-gel synthesis of nanoporous silica gels in an aqueous environment. Three distinct growth regimes emerge, depending on the solvent-to-silica ratio: compact nanoparticles, percolated silica networks, and branched clusters. These growth regimes can be identified on the basis of distinctive structural features. In the case of compact particles, the radial distribution functions exhibit a broad maximum that coincides with the radius of gyration of the aggregates, whereas in continuous networks the radial distribution function increases steadily beyond the near-range structural features. Furthermore, these growth regimes can be distinguished on the basis of the concentrations of structural defects, such as dangling bonds and residual OH groups. The growth kinetics of individual regimes are characterized by different relative contributions of atomic diffusion to the overall aggregation rate. Finally, the resulting gel structures possess different mechanical stability, as can be assessed by quantifying the extents of structural collapse during simulated supercritical drying.",
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N2 - Molecular dynamics simulations based on a reactive force field with charge transfer were used to model the sol-gel synthesis of nanoporous silica gels in an aqueous environment. Three distinct growth regimes emerge, depending on the solvent-to-silica ratio: compact nanoparticles, percolated silica networks, and branched clusters. These growth regimes can be identified on the basis of distinctive structural features. In the case of compact particles, the radial distribution functions exhibit a broad maximum that coincides with the radius of gyration of the aggregates, whereas in continuous networks the radial distribution function increases steadily beyond the near-range structural features. Furthermore, these growth regimes can be distinguished on the basis of the concentrations of structural defects, such as dangling bonds and residual OH groups. The growth kinetics of individual regimes are characterized by different relative contributions of atomic diffusion to the overall aggregation rate. Finally, the resulting gel structures possess different mechanical stability, as can be assessed by quantifying the extents of structural collapse during simulated supercritical drying.

AB - Molecular dynamics simulations based on a reactive force field with charge transfer were used to model the sol-gel synthesis of nanoporous silica gels in an aqueous environment. Three distinct growth regimes emerge, depending on the solvent-to-silica ratio: compact nanoparticles, percolated silica networks, and branched clusters. These growth regimes can be identified on the basis of distinctive structural features. In the case of compact particles, the radial distribution functions exhibit a broad maximum that coincides with the radius of gyration of the aggregates, whereas in continuous networks the radial distribution function increases steadily beyond the near-range structural features. Furthermore, these growth regimes can be distinguished on the basis of the concentrations of structural defects, such as dangling bonds and residual OH groups. The growth kinetics of individual regimes are characterized by different relative contributions of atomic diffusion to the overall aggregation rate. Finally, the resulting gel structures possess different mechanical stability, as can be assessed by quantifying the extents of structural collapse during simulated supercritical drying.

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