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Atomistic modelling of the structure and kinetics of silica-based sol-gel processes.

机译：基于二氧化硅的溶胶-凝胶过程的结构和动力学的原子建模。

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摘要

This thesis concerns the study of the structural and kinetic aspects of silica-based sol-gel processes, which we investigate using ab-initio and molecular mechanics computer modelling techniques. It is divided into five parts. The first is a general introduction to sol-gel processes. It contains four chapters, which describe the historical evolution of sol-gel processes, their technological importance, the current scientific background in the chemistry of silica-based processes and a guide to the principal sol-gel bibliography. The second part is a general introduction to atomistic modelling. It is divided in four chapters. The first is a brief historical overview focusing on the crescent motivation to apply computing methods. The second reviews ab-initio theory. The third is a review of molecular mechanics theory and the fourth is a guide on the main atomistic modelling bibliography.;The fourth part contains all molecular dynamics studies, aiming to create a realistic model to simulate sol-gel processes in solution. It contains four chapters. In the first, a model is developed to simulate liquids in a large range of thermodynamic conditions. This model is used in chapter two to study mixture and aggregation effects in diluted sol-gel solutions. The methodology developed in chapter one is enhanced in chapter three. This model is applied in chapter four to study aggregation and solvation effects in more realistic sol-gel solutions.;The fifth part is an overall discussion with two sections. The first summarises the implications of this work and considers possible directions for future studies. The second contains general considerations about the present and future of computer modelling. The thesis concludes with an alphabetical list of bibliography covering all references cited in the work.;The third part contains all density functional and Hartree-Fock studies, aiming to elucidate the structural growth and reaction mechanisms occurring in sol-gel processes. It contains seven chapters. Small species are analysed in chapter one to investigate the accuracy of the methods. The role of different silicate conformations is analysed in chapter two. In chapter three, the study of the silicate clusters is completed. All information is gathered in chapter four to create a growth kinetic model. The influence of the alkoxy groups is studied in chapter five. Solvation effects are investigated in chapter six. Hydrolysis and condensation reaction mechanisms are studied in chapter seven.
机译：本文涉及对基于二氧化硅的溶胶-凝胶过程的结构和动力学方面的研究，我们将使用从头开始和分子力学计算机建模技术进行研究。它分为五个部分。首先是对溶胶-凝胶工艺的概述。它包括四章，描述了溶胶-凝胶工艺的历史演变，其技术重要性，基于二氧化硅的工艺化学的当前科学背景以及主要的溶胶-凝胶参考书目指南。第二部分是对原子建模的一般介绍。它分为四个章节。首先是简要的历史概述，重点是应用计算方法的新月动机。第二部分回顾了从头开始理论。第三部分是分子力学理论的综述，第四部分是主要的原子建模参考书目指南。第四部分包含所有分子动力学研究，旨在创建一个模拟溶液中溶胶-凝胶过程的现实模型。它包含四章。首先，开发一个模型来模拟大范围热力学条件下的液体。在第二章中使用该模型研究稀释的溶胶-凝胶溶液中的混合和聚集效应。第一章中开发的方法在第三章中得到了增强。该模型将在第四章中应用，以研究更现实的溶胶-凝胶溶液中的聚集和溶剂化作用。第五部分是一个由两部分组成的整体讨论。第一部分总结了这项工作的意义，并考虑了未来研究的可能方向。第二部分包含有关计算机建模的现在和将来的一般注意事项。本文以书目字母顺序列表结尾，涵盖了该书中引用的所有参考文献。第三部分包含所有密度泛函和Hartree-Fock研究，旨在阐明溶胶-凝胶过程中发生的结构增长和反应机理。它包含七个章节。第一章对小物种进行了分析，以研究该方法的准确性。第二章分析了不同硅酸盐构象的作用。第三章完成了硅酸盐团簇的研究。第四章收集了所有信息，以创建生长动力学模型。第五章研究了烷氧基的影响。第六章研究了溶剂化作用。第七章研究了水解和缩合反应机理。

著录项

  • 作者

    Pereira, Jose Carlos G.;

  • 作者单位

    University of London, University College London (United Kingdom).;

  • 授予单位 University of London, University College London (United Kingdom).;
  • 学科 Physical chemistry.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 359 p.
  • 总页数 359
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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