Committee

Prof. Vladimir V. Tsukruk (Advisor), School of Materials Science and Engineering, Georgia Institute of Technology
Prof. Valeria T. Milam, School of Materials Science and Engineering, Georgia Institute of Technology
Prof. Paul S. Russo, School of Materials Science and Engineering and School of Chemistry & Biochemistry, Georgia Institute of Technology
Prof. Anju Toor, School of Materials Science and Engineering, Georgia Institute of Technology
Dr. Michael E. McConney, Materials and Manufacturing Directorate, Air Force Research laboratory
Dr. Robert J. Moon, Forest Products Laboratory, US Department of Agriculture, Forest Service

Abstract

One dimensional polysaccharide nanocrystals, derived from living organisms, can self-organize into complex structures that possess long-range hierarchical order making them great candidates for high-performance structural composites with multifunctional capabilities. Their abundance in nature and biodegradability makes them excellent candidates as sustainable materials of the future. However, a greater fundamental understanding of how these nanoscale building blocks organize into functional microstructures is needed to push the boundaries of mechanical and photonic metamaterials for the future. The goal of this thesis is to uncover the intrinsic mechanisms behind self-assembly phenomenon in natural systems, understand the critical forces and parameters required for their successful hierarchical organization into chiral nematic structure and with those insights manipulate the surface chemistry to create self-assembly templates for use in photonic films for optical filters, chiral encryption, smart coatings, or biosensors.
In this thesis, we first provide fundamental insight into how chiral interactions in 1D polysaccharide systems emerge, using cellulose nanocrystals (CNCs) as an example. Then, we show how CNCs interactions can be tuned and controlled via their surface modification. By functionalizing them with single stranded DNAs we show the possibility for CNCs chiral complexation through DNA guided assembly. A nanoscale-controlled strategy to induce stimuli responsiveness and dynamic chirality. The challenges of this process and strategies to overcome them are discussed. Lastly, a top-down 3D printing approach to engineer chiral CNC-based photonic crystals with unique optical activities is developed here. This method shows how thin films capable of controlled pre-programmed circularly polarized absorbance and emission can be constructed from CNC-composites for future smart coatings, optical encryption, or optical filters.
Overall, the goal of this work is to inspire applicational implementation of bioderived nanocrystals by demonstrating how their properties can be controlled and tailored based on the application. This work advances fundamental understanding of the assembly of polysaccharides nanocrystals in nature and creates a toolset to aid in the design and engineering of future metamaterials.