Opportunities

Carbon fibre composites provide state of the art performance, yet suffer limitations due to matrix dominated failures. By using a nanocomposite as the matrix, to create a hierarchical structure, many of these limiting properties can be improved. Nature uses hierarchical composites to striking good effect, even with poor constituent materials, in bone, shell, and other structures. We can use higher performance components, but have not yet explored the benefits of structuring across multiple lengthscales. This collaboration with NTU, Singapore will explore the use of nanocarbon composites as matrices for carbon fibre composites, using a unique processing route to incorporate high loadings of nanomaterials. This PhD vacancy is available for an immediate start, to UK or EU candidates.

Supervisors: Prof Thomas Anthopoulos, Prof Milo Shaffer (Imperial College)

Traditional materials metal oxides as anodes and low work function metals (Al, Ca, etc) as cathodes are expensive to deposit and are unsuited to flexible electronics due to brittleness or chemical instability towards atmospheric oxidants. Graphene has the potential to circumvent these problems, acting as a transparent electrode, exploiting its high conductivity at useful optical transmission, chemical stability, mechanical robustness and atomic smoothness. The central challenge is how to optimise the electronic properties of deposited films; the native work function (~4.6 eV) is not ideally-­‐suited for either anode/cathode electrodes, but is particularly unhelpful for cathodes, whilst typical sheet resistances are still high. In this project, we will prepare modified-­‐graphene / hybrid anode and cathode systems with controlled conductivity and work function, and demonstrate their integration with typical devices. Interestingly graphene/inorganic hybrids are also of particular interest for electrochemical electrodes need for supercapacitors and batteries. Printing thicker layers of such hybrids also offers the potential to generate useful energy storage and power management devices, integrated with the electronics. The approaches will build on our patented technologies to exfoliate and functionalise graphene sheets, combined with unique starting materials provided by commercial partners. The exfoliated graphenes are reduced and readily react with a variety of species, which will enable the production of hybrids inks, for deposition and testing. Further patented technologies allow the preparation of 3d crosslinked structures suitable for high surface area electrodes, using this basic chemistry. Available for candidates with a UK connection.

Individual perfect carbon nanotubes have axial stiffnesses roughly equal to that of diamond, and strengths ten times that of any other available material. There are, therefore, considerable efforts underway to exploit these properties in macroscopic composites. So far attention has focussed on nanotubes that are commercially available in bulk, but unfortunately these nanotubes are defective and have inferior intrinsic properties. This study will focus on attempting to exploit the remarkable properties of perfect nanotubes in real composite materials. This goal will require synthesis, treatment and/or purification of highly crystalline nanotubes. Appropriate surface chemistry will modify the interactions with model polymer matrices and the processing of the homogeneous composites. An understanding on the mechanical behaviour of such composites as a function of nanotube dimensions and other properties remains to be established. The long term goal of the project will be to explore new routes to preparing ultra-long nanotubes and or nanotube mesophases that will allow the fabrication of highly aligned composites. The work will be integrated with our large ‘Creativity in Composites’ program and exploit nanotube dispersion technology that we have recently licensed commercially.

Carbon nanotubes have provoked enormous interest in their fundamental behaviour and a wide variety of potential applications. For example, single-wall nanotubes may be metallic or semiconducting depending critically on their chirality. So far, single-wall nanotubes have been used to make the world’s smallest room temperature transistors and the most sensitive (bio-)electronic sensors. However, all of these applications require the selection of individual tubes with specific electronic character. Unfortunately, nanotubes are always synthesised as a mixture. This project explores new strategies to separate, functionalise, and supramolecularly assemble individual single-wall nanotubes. The strategy generalises to the bottom-up assembly of complex two and ultimately three dimensional networks of nanotubes with specified functionality. However, many of the intermediate structures are of great interest, particularly for thin film and flexible electronics.

Intrinsically, ideal graphene and related materials (GRMs) have exceptional properties and offer the potential for fundamental improvements in a wide range of applications. The ability to manifest these properties in useful macroscopic applications is intimately linked to the manufacturing processes and modification chemistry involved, which determine the nature and quality of the GRMs produced, as well as the extent of their dispersion in solvents (for inks) or matrices (for composites). The aim of the project will be to better understand the nature of GRM based products, using advanced techniques to map the locus of functionalization, and the three dimensional dispersion/orientation within, for example, polymer matrices. Available to UK students for an Autumn 2016 start.

To apply for any of these projects please send a CV and details of at least two referees to Dr. Milo Shaffer, Department of Chemistry, Imperial College, South Kensington, London, SW7 2AZ; m.shaffer "at" imperial.ac.uk