Liquid crystal phototonic materials derived from natural fibres

Despite the large variety of electronic devices based on liquid crystals (LCs) available, our society inexorably demands new attributes for the displays. Properties commonly requested are: faster, better, brighter, better colour, lighter, flexible, cheaper, environmentally friendly, and quite often, several of these improvements need to implemented at the same time. Therefore, apart from the exploration of new device modes, the search of new LC materials that show enhanced performance is critical to achieve these developments. One of the most widely found device is the (chiral) nematic display. In the chiral nematic phase, N*, the mesogens are aligned locally in a preferred orientation (the director) but the director describes a helical change over longer length scales, resulting in a helical assembly which shows a characteristic pitch, producing striking iridescence when the helical pitch is of the order of the visible light range. In Nature, the chiral nematic organisation is responsible for the vivid structural colour observed in beetles, butterfly wings, bird feathers and some fruits.

The dispersion of nanoparticles in liquid crystal hosts has shown to be an excellent avenue to discover new materials with improved properties. Usually the nanoparticles investigated (metallic, semiconductor, magnetic) are isotropic in shape; in addition they are difficult to disperse in the LC host, toxic and environmentally unacceptable. In this project we will use anisotropic nanoparticles derived from natural sources, functionalise them with a layer of mesogens (to make them miscible with liquid crystal hosts) and explore the behaviour of the liquid crystal-nanoparticle dispersions. Making use of this bio-inspired approach we will target liquid crystal nano-composites that show, among others, chiral nematic behaviour. Once we have synthesised these materials, we will use a variety of structural techniques to characterise the composites, such as SEM, TEM, small-angle X-Ray diffraction, neutron diffraction, polarised optical microscopy, DSC and confocal fluorescence microscopy, together with surface characterisation techniques, to gain an understanding of the nanoscale organisation. Ultimately, their applications as sensors and selective reaction media will be explored.

The graduate student working in this project will acquire very broad multidisciplinary skills combining organic synthesis, nanochemistry, macromolecular chemistry, physical and structural characterisation, LC behaviour and sensor applications. Collaboration with departmental colleagues and international collaborators is expected throughout the project. The student will get further training from the Chemistry courses as well as scientific writing and presentation skills through the iDTC programme in York, and external training in structural techniques when required. The student will be able to present and discuss the work at departmental events such as group meetings, poster sessions and seminars, and will be able to attend national and international conferences to present the work carried out and to network with researchers in related areas.

Shortlisting will take place as soon as possible after the closing date and successful applicants will be notified promptly. Shortlisted applicants will be invited for an interview to take place at the University of York on Friday 12 May. Candidates will be asked to give a short presentation prior to their interview by an academic panel. All research students follow our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills

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