Vapour-phase deposition of functional nanolayers

• Main Author: Wood, Thomas James
• Published: Durham University 2013
• Subjects: 540
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.567883

Vapour-phase deposition techniques have many advantages including being solventless and providing fine control (down to the nanometre level) of coating thickness. This thesis is about the use of both plasmachemical deposition and oxidative vapour-phase deposition to form functional coatings. Chapter 1 provides brief reviews of proton exchange membrane fuel cells and vapour-phase deposition techniques as well as an overall introduction to the thesis. Chapter 2 is a synopsis of the most commonly used experimental techniques used throughout this thesis (especial attention is focused on XPS and FTIR as they are used in every chapter). Chapters 3–4 record the use of plasmachemical deposition to form proton-conducting coatings for potential use in fuel cells. The strategy described is the use of anhydride precursors in order to produce layers with a high density of carboxylic acids. In chapter 4 these layers themselves are used as initiators to graft sulfonic-acid containing polymer brushes for the enhancement of proton conductivity. Chapter 5 describes the fabrication of poly(ionic liquid) layers by depositing an imidazole-containing precursor via pulsed plasmachemical deposition, which is subsequently quaternized via a vapour-phase reaction with 1-bromobutane. The resultant coatings show high values of ionic conductivity above 90 ◦C. In chapter 6 plasma enhanced chemical vapour deposition of metal(II) hexafluoroacetylacetonate precursors is used in order to produce metal-containing nanocomposite layers. The retention of an organic matrix and its chemical rearrangement under plasma conditions leads to high ionic conductivities. Chapters 7–8 utilize an atomized spray delivery system and plasma in conjunction with liquid precursor mixtures in order to form bioactive coatings (chapter 7) and nanocomposite layers (chapter 8) which show good adhesion and lithium-ion conductivity values. Finally chapter 9 utilizes the atomized spray system to deliver high vapour pressures of 3,4-ethylenedioxythiophene in the presence of triflic anhydride which acts as an oxidant. The ensuing vapour-phase reaction yields a conducting polymer coating.