Natasha Shirshova

Activation of structural carbon fibres for potential applications in multifunctional structural supercapacitors

The feasibility of modifying conventional structural carbon fibres via activation has been studied to create fibres, which can be used simultaneously as electrode and reinforcement in structural composite supercapacitors. Both physical and chemical activation, including using steam, carbon dioxide, acid and potassium hydroxide, were conducted and the resulting fibre properties compared. It was proven that the chemical activation using potassium hydroxide is an effective method to prepare activated structural carbon fibres that possess both good electrochemical and mechanical properties. The optimal activation conditions, such as the loading of activating agent and the burn-off of carbon fibres, was identified and delivered a 100-fold increase in specific surface area and 50-fold improvement in specific electrochemical capacitance without any degradation of the fibre mechanical properties. The activation process was successfully scaled-up, showing good uniformity and reproducibility. These activated structural carbon fibres are promising candidates as reinforcement/electrodes for multifunctional structural energy storage devices.

Ionic Liquids as Internal Phase for Non‐Aqueous PolyHIPEs

Stable high internal phase emulsions (HIPEs) with the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide as dispersed phase were prepared and polymerised thermally into polyHIPEs. All polyHIPEs exhibited pore morphologies similar to that of polyHIPEs obtained with an aqueous dispersed phase. PolyHIPEs containing the dispersed phase possess a low T(g) and are thermally stable in excess of 200 °C, offering the potential for new porous materials where water as dispersed phase is chemically or physically undesirable.

Mechanical, electrical and microstructural characterisation of multifunctional structural power composites

Multifunctional composites which can fulfil more than one role within a system have attracted considerable interest. This work focusses on structural supercapacitors which simultaneously carry mechanical load whilst storing/delivering electrical energy. Critical mechanical properties (in-plane shear and in-plane compression performance) of two monofunctional and four multifunctional materials were characterised, which gave an insight into the relationships between these properties, the microstructures and fracture processes. The reinforcements included baseline T300 fabric, which was then either grafted or sized with carbon nanotubes, whilst the baseline matrix was MTM57, which was blended with ionic liquid and lithium salt (two concentrations) to imbue multifunctionality. The resulting composites exhibited a high degree of matrix heterogeneity, with the ionic liquid phase preferentially forming at the fibres, resulting in poor matrix-dominated properties. However, fibre-dominated properties were not depressed. Thus, it was demonstrated that these materials can now offer weight savings over conventional monofunctional systems when under modest loading.

One step synthesis of MOF–polymer composites

Two different approaches for the one step synthesis of metal organic framework – polymer composites are discussed. An emulsion templating approach allows simultaneous MOF crystallization and polymerization of the internal phase of the emulsion resulting in the formation of porous MOF–polyHIPE composites.

Non-aqueous high internal phase emulsion templates for synthesis of macroporous polymers in situ filled with cyclic carbonate electrolytes

In order to develop inks suitable for roll-to-roll printing processes, which can be cured into in situ electrolyte filled high porosity macroporous polymer membranes, non-aqueous high internal phase emulsions (HIPEs) were prepared. The external phase of the formulated HIPEs consisted of lauryl methacrylate (LMA) and 1,14-tetradecanediol dimethacrylate (TDDMA) while a solution of bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) in a mixture of ethylene (EC) and propylene carbonate (PC) served as the internal phase. The stability of these non-aqueous HIPEs was strongly affected by the surfactant and the LiTFSI concentration in the internal phase. HIPE templates could only be polymerised when the LiTFSI concentration varied between 0.06 and 0.8 mol l−1. Electrochemical, thermal properties as well as morphology of the resulting polyHIPEs are discussed with respect to HIPE composition. The ionic conductivity of the resulting polyHIPEs was measured to be in the range from 4.18 to 8.64 mS cm−1.