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Title: Multiscale Model for the Templated Synthesis of Mesoporous Silica: The Essential Role of Silica Oligomers

Abstract

A detailed theoretical understanding of the synthesis mechanism of periodic mesoporous silica has not yet been achieved. We present results of a multiscale 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 closemore » agreement with experimental observations and strongly support a cooperative mechanism for synthesis of this class of materials. Furthermore, this work paves the way for tailored design of nanoporous materials using computational models.« less

Authors:
 [1]; ;  [2];  [3]; ; ;  [4]
  1. CICECO, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal, REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua Campo Alegre 687, 4169-007 Porto, Portugal, Laboratory of Separation and Reaction Engineering (LSRE), Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
  2. CICECO, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
  3. REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua Campo Alegre 687, 4169-007 Porto, Portugal
  4. Laboratory of Separation and Reaction Engineering (LSRE), Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal, Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
Publication Date:
Research Org.:
Univ. of Massachusetts, Amherst, MA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1247435
Alternate Identifier(s):
OSTI ID: 1434901
Grant/Contract Number:  
FG02-07ER46466
Resource Type:
Published Article
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Name: Chemistry of Materials Journal Volume: 28 Journal Issue: 8; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Pérez-Sánchez, Germán, Chien, Szu-Chia, Gomes, José R. B., D. S. Cordeiro, M. Natália, Auerbach, Scott M., Monson, Peter A., and Jorge, Miguel. Multiscale Model for the Templated Synthesis of Mesoporous Silica: The Essential Role of Silica Oligomers. United States: N. p., 2016. Web. doi:10.1021/acs.chemmater.6b00348.
Pérez-Sánchez, Germán, Chien, Szu-Chia, Gomes, José R. B., D. S. Cordeiro, M. Natália, Auerbach, Scott M., Monson, Peter A., & Jorge, Miguel. Multiscale Model for the Templated Synthesis of Mesoporous Silica: The Essential Role of Silica Oligomers. United States. doi:10.1021/acs.chemmater.6b00348.
Pérez-Sánchez, Germán, Chien, Szu-Chia, Gomes, José R. B., D. S. Cordeiro, M. Natália, Auerbach, Scott M., Monson, Peter A., and Jorge, Miguel. Wed . "Multiscale Model for the Templated Synthesis of Mesoporous Silica: The Essential Role of Silica Oligomers". United States. doi:10.1021/acs.chemmater.6b00348.
@article{osti_1247435,
title = {Multiscale Model for the Templated Synthesis of Mesoporous Silica: The Essential Role of Silica Oligomers},
author = {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},
abstractNote = {A detailed theoretical understanding of the synthesis mechanism of periodic mesoporous silica has not yet been achieved. We present results of a multiscale 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 cooperative mechanism for synthesis of this class of materials. Furthermore, this work paves the way for tailored design of nanoporous materials using computational models.},
doi = {10.1021/acs.chemmater.6b00348},
journal = {Chemistry of Materials},
number = 8,
volume = 28,
place = {United States},
year = {2016},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acs.chemmater.6b00348

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Cited by: 4 works
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