Porous Materials: Synthesis, Imaging, and Applications
11:00 - 11:30
Level 0, between bld. 4 and 5
Direct synthesis of hierarchical zeolites currently relies on the use of surfactant-based templates to produce mesoporosity by the random stacking of two-dimensional zeolite sheets or the agglomeration of tiny zeolite grains. In this talk, we will discuss the feasibility and the merits of using non-surfactant polymers as dual-function templates in the fabrication of hierarchical zeolites [1-2]. First, the minimal intermolecular interactions of non-surfactant polymers impose little interference on the crystallization of zeolites, favoring the formation of three-dimensionally continuous zeolite frameworks with a long-range order. Second, the mutual interpenetration of the polymer and the zeolite networks renders disordered but highly interconnected mesopores in zeolite crystals. These two factors allow for the synthesis of single-crystalline, mesoporous zeolites of varied compositions and framework types [1-2]. Third, extra functional groups in the polymer template can be utilized to incorporate desired functionalities into hierarchical zeolites . Last and most importantly, polymer-based templates permit heterogeneous nucleation and growth of mesoporous zeolites on existing surfaces, forming a continuous zeolitic layer . The advantages of hierarchical zeolites over conventional bulk zeolites as catalysts in different reactions will also be discussed. In the second part of this talk, we will introduce our recently developed method that enables the atomic-resolution TEM of MOFs that are extremely electron beam sensitive and therefore conventionally considered unexplorable by TEM. With this method, we successfully imaged a series of MOF materials with atomic resolution for the first time, and investigated their surface and interfacial structures .
 Zhu, J. et al., “Highly mesoporous single-crystalline zeolite beta synthesized using a non-surfactant cationic polymer as a dual-function template”, Journal of the American Chemical Society 2014, 136, 2503
 Tian, Q. et al., “Beyond Creation of Mesoporosity: the Advantages of Polymer-based Dual-function Templates for Fabricating Hierarchical Zeolites”, Adv. Func. Mater. 2016 dx.doi.org/10.1002/adfm.201504888
 Zhu, Y. et al., "Unravelling surface and interfacial structures of a metal-organic framework by transmission electron microscopy" Nature Materials 2017, in press