Year

2010

Degree Name

Doctor of Philosophy

Department

School of Chemistry

Abstract

Bionics is the revolutionary area of medical research concerned with the interface between biology and electronics. For the next generation of bionic devices, new electromaterials need to be developed. Conducting polymers are excellent candidate electromaterials for these bionic devices. Due to their ease of synthesis and functionalisation, polythiophenes are one of the best candidate conducting polymers. Here the synthesis and optimisation of novel polythiophene materials for bionic applications was investigated. The research focused on four key properties that are desirable for bionic materials; functionality, biodegradability, processability and biocompatibility.

The introduction of functionality into polythiophene materials was demonstrated through the synthesis of several terthiophene building blocks. Functionalisation of these terthiophene building blocks was demonstrated by the attachment of amino acid, barbituric acid and spiropyran functionalities. The functionalised terthiophenes could be polymerised to yield functional polymers. Spiropyran functionalised polymers were of particular interest as conformational changes in these materials could be electrically induced.

The development of biodegradable conducting polymers was initially investigated with the development of conducting azomethine linked thiophene oligomers. The stability of azomethine materials was investigated and they were found to be susceptible to acid hydrolysis. Then the synthesis of several novel terthiophene and sexithiophene oligomers via Stille coupling as precursors to biodegradable conducting polymers was explored.

Films and aligned electrospun fibres of ester functionalised poly(octanoic acid 2- thiophen-3-yl ethyl ester) were fabricated. Further functionalisation of these structures was demonstrated through hydrolysis of the ester and functionalisation of the films and fibres with ferrocene acid chloride. The electrochemistry and surface properties of these structures was compared with the hydrolysed structures being more hydrophilic and showing a much greater electrochemical response in aqueous electrolyte.

The biocompatibility of several polythiophene materials was tested with C2C12 muscle cells, which were shown to be compatible with these materials. Smoother spin coated films were seen to be better scaffolds than rough electropolymerised films, for supporting cell differentiation of sensitive ROSA primary muscle cells. Aligned polythiophene fibre structures on gold Mylar were investigated for controlling the direction of ROSA cell differentiation. Fibres spaced between 15-100 μm apart gave the best directional cues to the cells and most efficiently promote alignment of myotubes. The insights and knowledge gained during this study will help in the development and application of conducting polymer materials for bionic applications.

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