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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

HIGH-TEMPERATURE CONDUCTING POLYMERS

Zhifan Ke (17382937) 13 November 2023 (has links)
<p dir="ltr">Conducting polymers have garnered enormous attention due to their unique properties, including tunable chemical structure, high flexibility, solution processability, and biocompatibility. They hold promising applications in flexible electronics, renewable energies, sensing, and healthcare. Despite notable progress in conducting polymers over the past few decades, most of them still suffer from complicated synthesis routes, limited processability, low electrical conductivity, and poor ambient stability compared to their inorganic counterparts. Additionally, the susceptibility of conducting polymers to high temperatures makes them not applicable in real-life electronics. To address the challenges of developing high-performance and stable conducting polymers, we present two key approaches: dopant innovation for polymer-dopant interaction engineering and the discovery of new conjugated polymer hosts. From the perspective of dopant design, we first utilize cross-linkable chlorosilanes (C-Si) to design thermally and chemically stable conductive polymer composites. C-Si can form robust siloxane networks and simultaneously<i> </i>dope the host conjugated polymers. Besides, we have introduced a new class of dopants, namely aromatic ionic dopants (AIDs). The use of AIDs allows for the separation of doping and charge compensation, two processes involved in molecular doping, and therefore leads to highly efficient doping and thermally stable doped systems. We then provide insights into the design of novel conjugated polymer hosts. Remarkably, we have developed the first thermodynamically stable n-type conducting polymer, n-doped Poly (3,7-dihydrobenzo[1,2-b:4,5-b′]difuran-2,6-dione) (n-PBDF). n-PBDF is synthesized from a simple and scalable route, involving oxidative polymerization and reductive doping in one pot in the air. The n-PBDF ink is solution processable with excellent ink stability and the n-PBDF thin film is highly conductive, transparent, patternable, and robust. In addition, precise control over the doping levels of n-PBDF has been achieved through chemical doping and dedoping. By tuning the n-PBDF thin films between highly doped and dedoped states, the system shows controllable conductivity, optical properties, and energetics, thereby offering potential applications in a variety of organic electronics. Overall, this research advances the fundamental understanding of molecular doping and offers insights for the development of high-conductivity, stable conducting polymers with tunable properties for next-generation electronics.</p>
12

AN UNDERSTANDING OF MUSSEL ADHESION TO INFLUENCE MATERIALS DEVELOPMENT

Samuel L Huntington (8983913) 12 October 2021 (has links)
<p>The development of new materials has been inspired by lessons learned from natural systems. In the area of underwater adhesion and adhesives, inspiration has come from the complex protein adhesives generated by marine organism such as barnacle and mussels. These protein systems have a high incorporation of a unique amino acid, dihydroxyphenylalanine, and provides the unique adhesive qualities synthetic systems strive to emulate.</p> <p>By understanding how marine mussels stick to a variety of surfaces, new strategies can be explored for preventing the adhesion of biological organisms to various substrates. A continuous concern for marine vessels is the detrimental impact caused by biofouling on the hull of the ship. Fuel consumption can increase as the vessel’s drag increasing fuel consumption and non-native species can be introduced into new environments. Taking inspiration from catechol curing, new oxidative surfaces were investigated as potential antifouling coatings.</p> <p>Further insight into the marine mussels ability to apply and cure its adhesive on a variety of substrate has also inspired various synthetic polymers. The catechol moiety can be incorporated into a polymer backbone to give a new solvent based adhesive. Further investigation of the poly(styrene-co-(3,4-dihydroxystyrene)) adhesive system was done to formulate an underwater adhesive for unique use cases. A terpolymer was also explored as an ideal adhesive taking inspiration from the mussels by incorporating flexible, stiff, and sticky components to give a tunable adhesive.</p> <p>Having a strong bonding synthetic adhesive that can be used on a laboratory scale is good for academic investigation, but not of use outside the lab if it cannot easily be produced on a commercial scale. With the goal of large scale synthesis, a new polymerization method was introduced addressing some of the issues currently preventing commercial scale production.</p><br>

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