| Summary: | Computational tools have proved to be effective in the search for and design of better materials for a more sustainable planet. In this thesis, we look at two specific applications in two different sectors: industrial and transportation. Separations account for around half of the energy used in the industrial sector, and to reduce the energy used, there are efforts to convert some of the more energy intensive separation strategies like distillation to ones that use lesser energy like membrane-based technology. The first part of the thesis looks at the specific case of air or O₂/N₂ separation. Using a classical molecular dynamics (MD) framework to model gas permeation across a nanoporous graphene membrane temple, we observed increased selectivity, resulting from increasing adsorption energy differences alone. Using density functional theory calculations, we confirm that some transition metal oxides possess adsorption energies needed to operate as adsorption-based pore-flow membranes providing a suitable motivation to examine such membranes as a viable option for air separation.
In the transportation sector, there have been efforts to decrease the weight of the automobiles while still retaining the strength to decrease the fuel consumption and corresponding gas exhaust. In this work, we look at carbon fibers (CFs) as a candidate material. In this work, we use MD simulations to explore the processing and chemical phase space through a framework of CF models to identify their effects on elastic performance. We find that density, followed by alignment, and functionality of the molecular constituents dictate the CF mechanical properties more strongly than their size and shape. Lastly, we propose a previously unexplored fabrication route for high-modulus CFs achieved via generating high-density CFs which leads to CFs with isometric compressive and tensile moduli, enabling their potential applications for compressive loading. Finally, using this framework and by defining a parameter that can quantify crosslinking, we demonstrate that increasing the fraction of methyl functional groups increases the crosslinking and the elastic modulus.
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