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Title: Perylene diimide derived nanofibres and their applications
Author: Ho, Alexandra
ISNI:       0000 0005 0287 9925
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2020
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This thesis describes the synthesis and supramolecular structural directing methods of a perylene diimide derivative (PDI) for applications in aqueous metal-ion sensing and as a precursor for carbon nanofibres as electrode materials for supercapacitors. Perylene diimide derivatives are receiving increasing attraction due to their thermal stability and chemical inertness as well as their interesting electronic properties. Initially used as industrial grade pigments, more recent applications make use of its n-type semiconductivity which rises due to the high electron affinity of rylene dyes. In order to exploit their interesting potential applications, the initial insolubility of perylenebased molecules requires modification through substitution with primary amines (Nsubstitution). The soluble PDI was investigated for its susceptibility to pH-triggered selfassembly into fibres as well as fibre production through electrospinning using polyethylene glycol as a carrier polymer. Collected fibres could be carbonized at 800°C yielding carbon nanofibres (CNFs). PDI which could be dissolved in alkali aqueous conditions was sensitive to the presence of metal ions through UV-Vis absorbtion techniques. Dilute solutions of metal salts were added in microlitre-scale increments to cuvettes filled with PDI solution to record the UVVis response. PDI solutions provided a turn-off fluorescent sensor which was sensitive to the presence of metal cations within solution at low concentrations (2.5 nM) for iron (III) and copper (II) solutions. Further investigation is required into the effect of counter-ions. CNFs produced from ordered PDI molecules were assembled as an electrode for cyclic voltammetry capacitance testing. Using polyvinylidene fluoride (PVDF) as a binder in Nmethyl pyrrolidone (NMP), CNFs were adhered to a carbon electrode surface and cycled in an acid, alkali, and neutral electrolyte. Brunauer Emmett Teller analysis showed microporous materials with surface areas ~300m2 .g-1 and Raman spectroscopy was employed using ID/IG ratios as a measure of degree of graphetisation. Supramolecular CNFs demonstrated capacitances up to 247 F.g-1 (1 mV.s-1 ) while CNFs produced through electrospinning gave capacitances up to 427 F.g-1 (1 mV.s-1 ). Both materials demonstrated pseudocapacitive behaviour rather than that of pure electrochemical double-layer.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral