An Approach Towards Sustainable Synthesis of MXene and High-Performance Cementitious Composites
This thesis investigates innovative methods for synthesizing MXenes and enhancing cementitious materials to meet the critical need for sustainable manufacturing and improved mechanical properties in structural materials. Central to this research is the advancement in material science across two key areas: the development of environmentally friendly synthesis methods and the adoption of efficient manufacturing strategies to create advanced cement structures. A significant emphasis is placed on pushing the boundaries of material performance, sustainability, and synthesis techniques. For example, we explore modified approaches to MXene synthesis and the development of reinforced cementitious composites through the integration of nanotechnology and cutting-edge 3D printing technologies. The initial three chapters primarily concentrate on sustainable synthesis strategies for MXenes, including the exploration of alternatives to traditional hydrofluoric acid (HF) for removing aluminum (Al) from the MAX-phase. Due to HF's high toxicity and associated health and safety risks, we investigate the use of ammonium fluoride (NH4F) as a safe alternative. Our findings, supported by various analytical techniques, confirm NH4F's effectiveness in Al removal and in the production of 2D MXene flakes. Additionally, we explore a novel non-fluoride-based chemical method using iron chloride (FeCl2) as an etchant, which plays a dual role in etching and intercalating, leading to the production of high-quality Fe intercalated MXene flakes. Through detailed analysis, we evaluate the crystallinity, chemical composition, surface morphology, and defects of the MXene flakes produced by these new techniques. This part of the thesis not only aims to mitigate the environmental impact associated with MXene production due to HF use, but also to enhance their surface chemistry adaptability, broadening their application potential. Furthermore, the thesis chapters provide fundamental and an in-depth analysis of MXenes, in addition to highlighting the efficacy of these innovative synthesis techniques in maintaining the structural integrity and desired features of MXenes. The latter chapters, specifically chapters four and five, focus on enhancing the mechanical properties of cementitious materials by leveraging the unique properties of nanoparticles and the advancements in multi-material 3D printing. This section demonstrates significant improvements in compressive strength, toughness, and thermal management by incorporating hexagonal boron nitride (h-BN) into cement matrices. Additionally, it examines the application of direct ink writing (DIW) in creating reinforced cement and polyvinyl alcohol (PVA) structures, aiming to boost their impact resistance and energy absorption capabilities. Overall, this thesis offers a comprehensive overview of the synthesis, chemistry, and technologies involved in developing advanced materials with wide-ranging applications. For instance, the synthesized MXenes could be applied in electromagnetic interference shielding, catalysis, sensors, and flexible electronics. Conversely, the nanofiller and polymer-reinforced cement structures have potential applications in environments subjected to extreme thermal and mechanical stresses
Mxenes, HF-free etching, NH4F, FeCl2, Cement, Impact, hBN, Thermal Dissipation, Additive Manufacturing, PVA, polymer, Direct Ink Writing, Doping, Substitution
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