Date of Award
John B. Wiley
Matthew A. Tarr
Mark L. Trudell
Developing new materials with desired properties is a vital component of emerging technologies. Functional hybrid compounds make an important class of advanced materials that let us synergistically utilize the key features of the organic and inorganic counterparts in a single composite, providing a very strong tool to develop new materials with ”engineered” properties. The research presented here, summarizes efforts in the development of facile and efficient methods for the fabrication of three- and two-dimensional inorganic-organic hybrids based on layered oxide perovskites. Microwave radiation was exploited to rapidly fabricate and modify new and known materials. Despite the extensive utilization of microwaves in organic syntheses as well as the fabrication of the inorganic solids, the work herein was among the first reported that used microwaves in topochemical modification of the layered oxide perovskites. Our group specifically was the first to perform rapid microwave-assisted reactions in all of the modification steps including proton exchange, grafting, intercalation, and exfoliation, which decreased the duration of multi-step modification procedures from weeks to only a few hours. Microwave-assisted grafting and intercalation reactions with n-alkyl alcohols and n-alkylamines, respectively, were successfully applied on double-layered Dion-Jacobson and Ruddlesden-Popper phases (HLaNb2O7, HPrNb2O7, and H2CaTa2O7), and with somewhat more limited reactivity, applied to triple-layered perovskites (HCa2Nb3O10 and H2La2Ti3O10). Performing neutron diffraction on n-propoxy-LaNb2O7, structure refinement of a layered hybrid oxide perovskite was then tried for the first time. Furthermore, two-dimensional hybrid oxides were efficiently prepared from HLnNb2O7 (Ln = La, Pr), HCa2Nb3O10, HCa2Nb2FeO9, and HLaCaNb2MnO10, employing facile microwave-assisted exfoliation and post-exfoliation surface-modification reactions for the first time. A variety of surface groups, saturated or unsaturated linear and cyclic organics, were successfully anchored onto these oxide nanosheets. Properties of various functionalized metal-oxide nanosheets, as well as the polymerization of some monomer-grafted nanosheets, were then investigated for the two-dimensional hybrid systems.
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Akbarian-Tefaghi, Sara, "Microwave-Assisted Topochemical Manipulation of Layered Oxide Perovskites: From Inorganic Layered Oxides to Inorganic-Organic Hybrid Perovskites and Functionalized Metal-Oxide Nanosheets" (2017). University of New Orleans Theses and Dissertations. 2287.