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Silica aerogel-polymer nanocomposites and new nanoparticle syntheses.

机译：二氧化硅气凝胶聚合物纳米复合材料和新的纳米粒子合成。

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摘要

Aerogels are extremely high surface area, low density materials with applications including thermal and acoustic insulators, radiation detectors and cometary dust particle traps. However, their low density and aggregate structure makes them extremely fragile and practically impossible to machine or handle without breaking. This has led to the development of aerogel composites with enhanced mechanical properties through the addition of polymers or surface modifiers. To date, attempts to strengthen aerogels have come with significant increases in density and processing time. Here I will describe our search for a solution to these problems with our invention using methyl cyanoacrylate chemical vapor deposition (CVD) to strengthen silica, aminated silica and bridged polysilsesquioxane aerogels. This approach led to a strength improvement of the composites within hours and the strongest composite prepared had a 100x strength improvement over the precursor aerogel. We also developed the first approach to control the molecular weight of the polymers that reinforce silica aerogels using surface-initiated atom transfer radical polymerization (SI-ATRP). Although PMMA reinforcement of silica aerogels improved the mechanical properties, further strength improvements were achieved by cross-linking the grafted PMMA. Additionally, we developed the first silica aerogels reinforced with polyaniline nanofibers that were strong and electrically conductive. Reinforcing silica aerogels with polyaniline allowed them to be used as a sensor for the detection of protonating and deprotonating gaseous species. Finally we developed a new approach for the synthesis of silica and bridged polysilsesquioxane spheres using a surfactant free synthesis. This approach allowed for the first in-situ incorporation of base sensitive functionalities during the sol-gel polymerization.
机译：气凝胶是极高的表面积，低密度的材料，其应用包括隔热和隔音，辐射探测器和彗星尘埃捕集器。但是，它们的低密度和聚集结构使其非常脆弱，几乎不可能在不破裂的情况下进行机械加工或处理。通过添加聚合物或表面改性剂，开发了具有增强的机械性能的气凝胶复合材料。迄今为止，增强气凝胶的尝试已伴随着密度和加工时间的显着增加。在这里，我将描述我们通过使用氰基丙烯酸甲酯化学气相沉积（CVD）来增强二氧化硅，胺化二氧化硅和桥接聚倍半硅氧烷气凝胶的发明来寻求解决这些问题的方法。这种方法可以在数小时内提高复合材料的强度，并且所制备的最坚固的复合材料的强度比前体气凝胶高100倍。我们还开发了第一种方法来控制使用表面引发的原子转移自由基聚合（SI-ATRP）增强二氧化硅气凝胶的聚合物的分子量。尽管二氧化硅气凝胶的PMMA增强可以改善机械性能，但通过将接枝的PMMA交联可以进一步提高强度。此外，我们开发了第一款用聚苯胺纳米纤维增强的二氧化硅气凝胶，该凝胶坚固且导电。用聚苯胺增强二氧化硅气凝胶可以将它们用作检测质子化和去质子化气态物质的传感器。最后，我们开发了一种使用无表面活性剂的合成方法合成二氧化硅和桥联的倍半硅氧烷球的新方法。该方法允许在溶胶-凝胶聚合过程中首次就地引入碱敏感性官能团。

著录项

  • 作者

    Boday, Dylan Joseph.;

  • 作者单位

    The University of Arizona.;

  • 授予单位 The University of Arizona.;
  • 学科 Chemistry Polymer.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 326 p.
  • 总页数 326
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 高分子化学（高聚物）;工程材料学;
  • 关键词

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