A multi-scale model for the templated synthesis of mesoporous silica : the essential role of silica oligomers

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Pérez-Sánchez, Germán and Chien, Szu-chia and Gomes, José R. B and D. S. Cordeiro, M. Natália and Auerbach, Scott M. and Monson, Peter A. and Jorge, Miguel (2016) A multi-scale model for the templated synthesis of mesoporous silica : the essential role of silica oligomers. Chemistry of Materials, 28 (8). pp. 2715-2727. ISSN 0897-4756 (https://doi.org/10.1021/acs.chemmater.6b00348)

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Abstract

A detailed theoretical understanding of the synthesis mechanism of periodic mesoporous silica has not yet been achieved. We present results of a multi-scale simulation strategy that, for the first time, describes the molecular-level processes behind the formation of silica/surfactant mesophases in the synthesis of templated MCM-41 materials. The parameters of a new coarse-grained explicit-solvent model for the synthesis solution are calibrated with reference to a detailed atomistic model, which itself is based on quantum mechanical calculations. This approach allows us to reach the necessary time and length scales to explicitly simulate the spontaneous formation of mesophase structures, while maintaining a level of realism that allows for direct comparison with experimental systems. Our model shows that silica oligomers are a necessary component in the formation of hexagonal liquid crystals from low concentration surfactant solutions. Because they are multiply charged, silica oligomers are able to bridge adjacent micelles, thus allowing them to overcome their mutual repulsion and form aggregates. This leads the system to phase separate into a dilute solution and a silica/surfactant-rich mesophase, which leads to MCM-41 formation. Before extensive silica condensation takes place, the mesophase structure can be controlled by manipulation of the synthesis conditions. Our modeling results are in close agreement with experimental observations and strongly support a co-operative mechanism for the synthesis of this class of materials. This work paves the way for tailored design of nanoporous materials using computational models.

ORCID iDs

Pérez-Sánchez, Germán, Chien, Szu-chia, Gomes, José R. B, D. S. Cordeiro, M. Natália, Auerbach, Scott M., Monson, Peter A. and Jorge, Miguel ORCID logoORCID: https://orcid.org/0000-0003-3009-4725;
  • Item type:Article
    ID code:56076
    Dates:
    Date
    Event
    26 April 2016
    Published
    4 April 2016
    Published Online
    4 April 2016
    Accepted
    Notes:“This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Chemistry of Materials, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/acs.chemmater.6b00348
    Subjects:Science > Chemistry
    Department:Faculty of Engineering > Chemical and Process Engineering
    Depositing user: Pure Administrator
    Date deposited:05 Apr 2016 08:58
    Last modified:16 Dec 2024 20:50
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/56076
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