Deformation of hierarchical and anisotropic porous solids by fluid adsorption

这项研究的目的是加强对具有分级孔隙率的整体材料中吸附引起的变形的基本理解。由具有微孔壁的有序介孔二氧化硅组成的大孔网络将被合成，同时控制孔尺寸、孔体积分数，特别是在所有层次上的孔各向异性。吸附引起的变形将在中孔系统水平和宏观水平上进行定量研究。这项研究的中心动机是在纳米尺度上推导吸附诱导变形的物理化学参数与层次化和各向异性网络结构之间的基本关联，并由此在宏观水平上驱动力学行为。这些知识为分层组织的多孔系统在设计的可切换部件中的未来应用奠定了基础。这项研究的基本目标和创新方面如下：将开发新的合成方法，在控制流体-壁面相互作用和微孔率的同时，在不同水平上定制具有分级孔隙率的单块二氧化硅的各向异性程度。合成是基于剪切或单轴压缩等外力场作用下的溶胶-凝胶路线。模型碳和硅的复制将分别通过硬模板和反应转化，不同的长度尺度和各向异性将被明确考虑在实验上的吸附诱导变形的研究。使用基于同步辐射的技术的结构研究将允许在所有尺度上表征结构。在流体吸附过程中应用的一种独特的原位技术组合(原位X射线衍射法和原位膨胀法)将被用来定量地得出在纳米水平上层级对流体诱导变形的宏观响应的影响。指定的模型流体为正戊烷和氮气，用于推导基本关系式，将水指定为更复杂的吸附，用于应用。将开发和验证吸附诱导变形的分层力学模型。它们基于单个中孔变形的解析和/或数值模型，并结合有限元计算来推导宏观应变。该项目结合了奥地利和德国三个实验小组的独特和互补的专门知识，并得到了一个致力于吸附诱导变形理论的国际合作伙伴的支持。这一基础研究项目的预期结果被认为对致力于更好地理解吸附引起的变形的理论家和建模小组以及开发用于传感和驱动、与能源相关的应用和催化的设备的应用科学家都是有益的。

The goal of the proposed research is to enhance the fundamental understanding of adsorption-induced deformation in monolithic materials with hierarchical porosity. Macroporous networks consisting of struts of ordered mesoporous silica with microporous walls will be synthesized, while controlling pore size, pore volume-fraction, and particularly also pore anisotropy at all hierarchy levels. Adsorption-induced deformation will be investigated quantitatively at the level of the mesopore system as well as on the macroscopic level. The central motivation for the proposed research is to derive basic correlations between the physico-chemical parameters of adsorption-induced deformation at the nanometer scale, and the hierarchical and anisotropic network structure with resulting actuated mechanical behavior at the macroscopic level. This knowledge forms the basis for future applications of hierarchically organized porous systems in designed switchable components. The basic goals and innovative aspects of the proposed research are the following:New synthesis approaches will be developed to tailor the degree of anisotropy in monolithic silica with hierarchical porosity at different levels, while controlling fluid-wall interaction and microporosity. Synthesis is based on sol-gel routes under external force fields such as shear or uniaxial compression. Model carbon and silicon replica will be derived from these silica monoliths by hard templating and reactive conversion, respectively.Different length scales and anisotropy will be explicitly considered experimentally in the investigation of adsorption-induced deformation. Structural investigations using synchrotron radiation based techniques will allow characterizing structure at all scales. A unique combination of in-situ techniques applied during fluid adsorption (in-situ X-ray diffraction and in-situ dilatometry) will be used to quantitatively derive the influence of hierarchy on the macroscopic response to the fluid induced deformation at the nanometer level. Designated Model fluids will be n-Pentane and N2 for derivation of fundamental relationships and H2O as a more complex adsorptive towards applications.Hierarchical mechanical models of adsorption-induced deformation will be developed and validated. They are based on analytical and/or numerical models for single mesopore deformation, coupled with finite element calculations to derive the macroscopic strains. The project combines unique and complementary expertise of three experimental groups in Austria and Germany, supported by an international cooperation partner working on the theory of adsorption- induced deformation. The expected outcomes of this basic research project are believed to fertilize both, theoreticians and modeling groups working on a better understanding of sorption-induced deformation in general, as well as applied scientists developing devices for sensing and actuation, for energy related application, and for catalysis.