Synthesis and Functionalisation of Novel, Processable Polythiophene and Polypyrrole Derivatives

Abstract

Conducting polymers are materials of great interest due to their metallic-like conductivity while retaining the characteristics of conventional polymers, such as the flexibility of processing and the ease of synthesis. The organic nature of conducting polymers allows the materials to be readily modified and thus there is strong interest in the functionalisation of these materials. This thesis focuses on two classes of polymers, polythiophene phenylene (PThP) and polypyrrole phenylene (PPyP). Both of these polymers have better electrochemical properties compared to the parent polymer due to the electron-donating alkoxy substituents that can be incorporated in the central phenylene. The alkoxy substituents also provide a handle for the incorporation of a range of functional side chains. Thus, novel ThPs and PyPs with side chains bearing di-ethylene glycol (43 and 128), tri-ethylene glycol (44 and 129), azide (45 and 130), radical initiating sites (46, 47 and 131) and carboxylic acid (48 and 132) were synthesised and their electrochemical behaviour analysed. Following the monomer synthesis, a selection of these monomers were copolymerised and the side chains further functionalised through the use of ‘click’ chemistry and grafting of brushes using ATRP. The alteration of physical properties through ATRP grafting was used to improve the solubility of the polymer whereas ‘click’ chemistry was utilised to attach complex molecules and bestow additional functionalities. The synthesised PThP and PPyP were electrospun, in a blend of either PEO or PLGA, into nanofibre mats.