Building a Sustainable Future through the Material design of 3D Printed Polymer Materials
Type of DegreePhD Dissertation
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3D printing technologies are coming to the forefront of scientific, industrial, and public attention as it allows customized manufacturing of complex parts with a high degree of control over design, processing parameters, and time. However, compared to parts fabricated by traditional methods, 3D printed composites typically show poorer mechanical strength and thereby increased potential for material damage and failure during fabrication and use. Here, we incorporate self-healing properties towards extending the lifetimes of 3D printed polymeric objects. Inspired by biological self-healing, in which a damage event triggers an autonomic healing response, microcapsules containing healing agents can be embedded into a host material. During a damage event, these microcapsules rupture, release the healing agent, and heal the surrounding material by polymerization, entanglement, or cross-linking. Double shell wall polyurethane/poly-(urea-formaldehyde) microcapsules are synthesized by in-situ-interfacial polymerization. Microcapsules with solvent and monomer core fluids are prepared to investigate solvent-healing and monomer self-healing mechanisms. Microcapsules containing healing agents are either incorporated into the host polymer matrix or are coated onto 3D printing polymer filaments to create 3D printed objects capable of self-healing. Microcapsule distribution within composites is visualized using X-ray Nano-CT imaging. Microcapsule survivability and self-healing properties of these composite materials after 3D printing are evaluated via examining the healing efficiency and mechanical strength of the 3D printed objects. These results lay the foundation for including self-healing behavior into 3D printed polymer composites. Additionally, the application of 3D printing as a platform for geoscience applications by using a variety of polymer materials to replicate reactive porous media samples is investigated towards understanding of subsurface systems towards improving the human and planetary conditions in the future.