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nematic polymer and elastomer particles

Davey, Kirsty Leigh (2015) nematic polymer and elastomer particles. PhD thesis, University of York.

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Abstract

The creation of nematic polymer and elastomer particles in the micrometre size range with responsive properties by heterogeneous polymerisation techniques, specifically dispersion polymerisation and RAFT-assisted dispersion polymerisation, is reported. Control of size, size-distribution and confinement texture was achieved. A novel monomer design with a systematic approach was adopted in order to determine the effect of mesogen structure on the director configuration that would result within microscale nematic polymer particles, which revealed a change in the director configuration on the increase of just one CH2 group on the side chains of the mesogen. This change in the director configuration revealed radial particles within polar solvents without the addition of a further surface analyte, and allowed for the controlled creation of nematic polymer particles with specific internal confinement textures, including the formation of an escaped twisted radial structure created through copolymerisation of two different nematic monomers. Careful investigations and modifications of dispersion polymerisation with the addition of a RAFT agent allowed for the synthesis of microscale nematic elastomer particles with confirmed network formation, a discovery that is previously unreported. These elastomeric particles were reversibly responsive to changes in their external environment, by showing confinement textures after swelling which correspond to the polarity of the solvent. The particles were also responsive to changes in temperature and survived multiple heat and cool cycles which is further indication of successful network formation. Electro-optical investigations of nematic polymer particles showed the reversible shape deformation of free nematic polymer particles as a result of the internal mesogenic units aligning with the field. This deformation is only observed with polymeric particles with a low glass transition temperature as the flexible polymer chains allow for mesogen reorientation, and is a different behaviour to what has been reported previously for low molecular weight droplets in an electric field.

Item Type: Thesis (PhD)
Academic Units: The University of York > Chemistry (York)
Identification Number/EthosID: uk.bl.ethos.665055
Depositing User: Mrs Kirsty Leigh Davey
Date Deposited: 03 Sep 2015 12:29
Last Modified: 08 Sep 2016 13:33
URI: http://etheses.whiterose.ac.uk/id/eprint/9729

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