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Title: Synthesis, self-assembly and applications of functional amphiphiles based on oligo(aniline)
Author: Bell, Owen Alexander
ISNI:       0000 0004 5994 8701
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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Self-assembly is a promising route to provide functional nanomaterials that meet technological challenges in organic electronics, energy storage and biomaterials. Oligomers of aniline are switchable, conductive organic materials that can self-assemble, mimicking the properties of the well-known conducting polymer poly(aniline) but with improved solubility and versatility for applications. In this thesis, the preparation of a family of amphiphiles based on oligo(aniline) is described. The structure of these species, bearing a cationic headgroup common to surfactants, was designed to endow water-solubility and thus provide a strong driving force for the hydrophilic oligo(aniline) section to self-assemble. The headgroup structure was varied to include several different quaternary amines, and the self-assembly of a trimethylammonium-bearing oligo(aniline) amphiphile in water was investigated in detail. Investigations by electron microscopy, UV-Vis spectroscopy and X-ray diffraction showed isodesmic self-assembly into one-dimensional anisotropic nanowires of single-molecule thickness occurred in a manner typical of chromonic liquid crystals, and the arrangement of oligo(aniline)s within self-assemblies was elucidated. Self-assembled helical conductive nanowires were produced in water by ionic complexation of single-enantiomer camphorsulfonic acid with oligo(aniline) amphiphiles, as observed by circular dichroism, four-point probe resistance and UV-Vis spectroscopy measurements. A variety of other · strong organic acids were found to promote self-assembly into fibrous or spherical structures; proof of principle that oligo(aniline) is a versatile platform for construction of supramolecular functional materials. Oligo(aniline) amphiphiles were used to address an important technological challenge by dispersing carbon nanotubes in water. Dispersion conditions were investigated and optimised by UV-Vis and electron microscopy, and the resulting oligo(aniline)-carbon nanotube dispersions were used to fabricate flexible all-organic electrochemical capacitors for energy storage. Oligo(aniline) amphiphiles are found to be promising for highly ordered, tunable, functional supramolecular materials. This work provides understanding and a basis for their further development.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available