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Author ORCID Identifier

https://orcid.org/0000-0002-2715-5198

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Polymer Science and Engineering

Year Degree Awarded

2021

Month Degree Awarded

May

First Advisor

Kenneth R. Carter

Subject Categories

Polymer and Organic Materials | Polymer Science

Abstract

Governments and scientists all over the planet have recognized the importance of pursuing and achieving sustainability. As the human population grows and technologies advance, the planet’s limited resources become less and less able to support our taxing demands. In 2015, the United Nations set forth 17 Sustainable Development Global Goals. Goal 12 “Responsible Production and Consumption” can be addressed quite readily by the integration of sustainable materials into advanced technologies; however, such materials have yet to be developed. Cellulose nanocrystals (CNCs) – an abundant, well-known sustainable nanomaterial hydrolyzed from bulk cellulose with high surface functionality and high strength properties – have immense potential as building blocks for sustainable composites, but very few synthetic and analytical strategies used to produce and learn about these composites are currently understood. This dissertation work describes synthetic methods and analytical techniques used to develop and characterize CNC composite materials. CNCs were exchanged from water into anhydrous organic media via extensive viii solvent exchange procedures, thereby enabling water-sensitive surface modifications using a variety of organic small molecule and polymer syntheses. Surface bound materials imparted an array of properties non-native to cellulosic materials. These composite materials combined the sustainable substrate properties of CNCs with properties desirable in advance applications. Through a series of investigations, families of novel CNC derivatives were designed and produced including a semiconducting CNC/polyfluorene emitter material and a t-Boc modified CNC hydrophobic coating material. Semiconducting grafted polyfluorene-CNC composites sported grafted polymer molecular weights above the effective conjugation length of polyfluorene and, when employed as an OLED emitter layer, proved to have comparable properties with homopolymer polyfluorene standards. Small molecule t-Boc modified CNC composites demonstrated hydrophobic behaviors that, when complemented with a photoacid generator, could be cast into films and coatings and subsequently photopatterned to yield selectively designed water guiding or confining channels. Furthermore, numerous synthetic and processing parameters were determined to give precise control of properties, thus giving a single CNC derivative immense versatility and applicability. The results of this work unveil how novel CNC composites can be designed for sustainable advanced technologies.

DOI

https://doi.org/10.7275/22181256.0

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