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AZOBENZENE-BASED POLYMERS FOR ORGANIC ELECTRONICS AND PHOTO-THERMAL BATTERIES

Abstract
Azobenzene-based polymers have been largely investigated due to their excellent physical properties and flexibilities for organic electronics and photo-thermal batteries. Molecular-scale controls and morphological controls of the functional materials are major elements to tune structure-property relationship as well as achieve desirable properties for the functional materials. This body of work aims to provide a molecular-scale or morphological control to modify physical properties of CNTs or photo-thermal batteries (PTBs) with light-responsive azobenzene polymers. CNTs are one of the main components in organic electronic devices and I demonstrate facile and effective ways to modify physical properties of CNTs, and I apply molecular/macromolecular-scale tuning in the fabrication of special dispersant for metallic CNTs and electrically modulated MWCNT composite. With HBC’s strong affinity with MWCNT surface, PMMA end-functionalized with single HBC unit (HBC-PMMA) is successfully developed for dispersing heavy metallic MWCNTs in a solvent for easy processability. Light-responsive dispersant containing azobenzene unit is also designed to control dispersity of MWCNT through control of dipole-dipole interaction between MWCNTs under different light alteration. With light-responsive azobenzene polymer, electrically modulated MWCNT composite is fabricated and studied to understand electrical behaviors of the metallic CNT composite under different stimuli. I demonstrate that azobenzene unit plays an important role in resistive modification of MWCNTs through the formation of π-stacking of the E-isomers during azobenzene isomerization. Moreover, I demonstrate that azobenzene-based syndiotactic polymer is a promising scaffold for high energy density of PTBs. Also, solvent-polymer interactions should be considered to fabricate optimal morphologies of the polymer for high energy density, and different solvent processing can change physical polymer properties to tune energy density, heat-release shape, and stability of the PTBs. I also demonstrate that azobenzene polymer backbone and sidechain modification is important to tune stability as well as energy density of the PTBs. Modifying backbone structure of the polymer containing azobenzene is an effective tuning method to control stability of the azobenzene-based PTBs. Also, different sidechain modification of azobenzene polymer can tune energy density via space control or azo-population control, or both.
Type
campusfive
dissertation
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Publisher
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License
http://creativecommons.org/licenses/by-nc-nd/4.0/