Integrating polarisation effects into non-polarisable models to better model the self-assembly of mesoporous silica nanomaterials

Student thesis: Doctoral Thesis

Abstract

Mesoporous silica nanomaterials are a class of materials of rapidly growing importance. Despite this, many details of their synthesis are still poorly understood. For this reason, computational studies have been widely used to further our understanding of the processes involved at the molecular level. Unfortunately, many of these models are either too generic or specialised for general use and neglect phenomena that play an important role in the synthesis process, such as polarisation.For this reason, this thesis had two main goals: 1) to develop new methodologies to integrate polarisation effects into fixed-charge force fields; 2) to employ these new insights into a generic, transferable force field for organosilica molecules. In this work, we demonstrated that the current modelling paradigm for water, the solvent in which mesoporous silica synthesis takes place, is fundamentally flawed when it comes to accounting for the cost of polarisation in the free energy.We have therefore proposed a new, more detailed analytical correction that can obviate this current failing of classical non-polarisable force fields. Subsequently, we carried out a detailed analysis of different methodologies for obtainingpoint charges suitable for the liquid phase from quantum-mechanical calculations. Finally, we employed quantum-mechanical calculations, molecular dynamics simulations and polarisation corrections to parametrise models for organosilica molecules.This was then used to propose a molecular model for silicic acid, the principal precursor in the synthesis of mesoporous silica, via transferability. In future, we plan to expand our proposed transferable force field to a wider range of organosilica molecules, thereby facilitating the simulation of the silica synthesis with a much wider range of organosilica precursors. This would be advantageous for the discovery of new, in situ functionalised mesoporous silica nanomaterials.
Date of Award30 Jun 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council) & University of Strathclyde
SupervisorMiguel Jorge (Supervisor) & Demosthenes Kivotides (Supervisor)

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