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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2022)

Protective coatings are commonly used to extend the service life of components or structures to provide a barrier against unexpected damage and harsh environments by improving the surface hardness, corrosion resistance, or oxidation resistance of materials. The objective of this research is to develop a biomimetic coating inspired by the impact resistant nanocomposite coating found on the dactyl club of the Odontodactylus scyllarus (i.e., the peacock mantis shrimp). These scalable sacrificial coatings would provide added impact protection to core structural components to extend their service life or to prevent catastrophic failure during impacts or collisions. This study will investigate the protective capabilities of a manmade analog comprised of inorganic (silicon carbide) nanoparticles embedded within an organic (chitosan) matrix. By varying particle loading, we can modulate the extent of energy dissipation and damping. Drop casting or spray deposition methods are used to yield thin-film coatings which localize damage and decrease penetration depth, thus protecting underlying substrates and improving overall impact resistance. The results show that up to a certain degree, additional particle loading improves impact resistance, which shows promise in potential implementations in the automotive, aerospace, and energy industries without adding significant weight.

    Cover page: Bio-inspired impact resistant coatings
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2024)
    In vat polymerization (VP) 3D printing, there is an urgent need to expand characterization efforts for resins derived from natural resources to counter the increasing consumption of fossil fuels required to synthesize conventional monomers. Here, we apply multiscale mechanical characterization techniques to interrogate a 3D printed biobased copolymer along a controlled range of monomer ratios. We varied the concentration of two dissimilar monomers to derive structural information about the polymer networks. Current research primarily considers the macroscale, but recent understanding of the process-induced anisotropy in 3D printed layers suggests a multiscale approach is critical. By combining typical macroscopic techniques with micro- and nanoscale analogues, clear correlations in the processing-structure-property relationships appeared. We observed that measured moduli were always greater via surface-localized methods, but property differences between formulations were easier to identify. As researchers continue to develop novel sustainable biopolymers that match or exceed the performance of commercial resins, it is vital to understand the multiscale relationships between the VP process, the structure of the formed polymer networks, and the resultant properties.
      Cover page: Multiscale mechanical characterization of biobased photopolymers towards sustainable vat polymerization 3D printingCreative Commons 'BY-NC-ND' version 4.0 license
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2022)
      A fine control over different dimensional scales is a challenging target for material science since it could grant control over many properties of the final material. In this study, we developed a multivariable additive manufacturing process, direct ink write printing, to control different architectural features from the nano- to the millimeter scale during extrusion. Chitin-based gel fibers with a water content of around 1500% were obtained extruding a polymeric solution of chitin into a counter solvent, water, inducing instant solidification of the material. A certain degree of fibrillar alignment was achieved basing on the shear stress induced by the nozzle. In this study we took into account a single variable, the nozzles internal diameter (NID). In fact, a positive correlation between NID, fibril alignment, and mechanical resistance was observed. A negative correlation with NID was observed with porosity, exposed surface, and lightly with water content. No correlation was observed with maximum elongation (~50%), and the scaffolds excellent biocompatibility, which appeared unaltered. Overall, a single variable allowed a customization of different material features, which could be further tuned, adding control over other aspects of the synthetic process. Moreover, this manufacturing could be potentially applied to any polymer.
        Cover page: Direct Ink Write Printing of Chitin-Based Gel Fibers with Customizable Fibril Alignment, Porosity, and Mechanical Properties for Biomedical Applications.
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