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Title: Synthesis and applications of double-gyroid-structured functional materials
Author: Scherer, Maik
ISNI:       0000 0004 5364 5697
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2014
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The objective of this work, concerning the template-assisted patterning of functional materials on the nanoscale to enhance specific material properties, is five-fold. Firstly, to develop a highly reproducible synthesis pathway for large quantities of double- gyroid-forming diblock copolymers. Secondly, to replace the previously used fluo- rinated monomers with an inexpensive and environmentally sustainable alternative making large-scale applications feasible. Thirdly, to establish a reliable and fast fabri- cation technique for fully porous gyroidal templates. Fourthly, to replicate these tem- plates with inorganic as well as organic functional materials using electrochemical and atomic layer deposition. Finally, to apply and characterize these novel double-gyroid- structured materials in devices such as photovoltaic devices, electrochromic displays, and supercapacitors. The first part of this thesis introduces the different techniques of modern nanotechnol- ogy employed in three-dimensional nanopatterning of functional materials and seeks to highlight the possibilities and advantages of using self-assembled, mesoporous polymeric templates for this purpose. Chapter 2 explores the fascinating gyroidal intermaterial dividing surfaces formed by self-assembling systems, such as microphase separating di- block copolymers. Chapter 3 focuses on the synthesis of double-gyroid-forming diblock copolymers consisting of poly(4-X-styrene) and poly(lactic acid) via atom transfer radi- cal and organocatalytic ring-opening polymerization using a bifunctional initiator. The preparation of mesoporous templates with double-gyroid morphology based on a rapid thermal annealing protocol is described in Chapter 4. Importantly, it is shown that copolymers prepared from inexpensive, non-substituted styrene can yield fully porous thin films. Chapter 5 reports the template-assisted electrodeposition of metal oxides, such as V2O5, using the previously prepared voided styrenic templates. Further, the perfor- mance of these materials as electrodes in electrochromic displays and supercapacitors is tested. Chapter 6 describes an alternative approach to obtain double-gyroid-structured metal ceramics via the post-nanostructuring thermal oxidation of electroplated metals. Nickel is chosen to demonstrate this highly versatile fabrication route and to study the nanoscale Kirkendall effect of three-dimensional structures. Further, the electrochromic performance of NiO is investigated. Chapter 7 deals with yet another electrodeposition technique, namely the electropolymerization of conjugated polymers. Identification of suitable solvents for the templated electrosynthesis and the subsequent template dis- solution enable the three-dimensional nanopatterning of PPy, PEDOT, and PT. The refilling of the organic template via atomic layer deposition, including the necessary chemically modification of the styrenic scaffold for an improved thermal resistance and surface functionality, is discussed in Chapter 8.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral