TY - CONF

T1 - Control of the director configuration in liquid crystal polymer colloids

AU - Görtz, Verena

PY - 2013

Y1 - 2013

N2 - Liquid-crystalline droplets and polymer particles display unique director configurations because the liquid-crystalline order is confined within non-planar topologies. The director configurations observed result from a balance between bulk and surface interactions and are therefore dependent on parameters such as particle size, host polarity and temperature.We used polar dispersion polymerization to create monodisperse polymer particles in the low micrometer range from a series of nematic monomers with lateral mesogen attachment. In this series of particles we observed a remarkable switch of the director configuration from bipolar to radial as a result of a small increase in the length of alkyl chains on the mesogen.A copolymerization study using mixtures of monomers which display bipolar or radial textures revealed a third confinement texture which was assigned as the twisted radial director configuration.Furthermore, we were able to observe a reversible switch in the director configuration in response to a change in the solvent polarity.In summary, our research reveals that the ordering in nematic polymer particles is influenced by subtle changes in the mesogen structure and that reversible ordering transitions are triggered by changes in the host environment. A clear change in the optical appearance of the particles is observed which provides a mechanism for sensor applications.

AB - Liquid-crystalline droplets and polymer particles display unique director configurations because the liquid-crystalline order is confined within non-planar topologies. The director configurations observed result from a balance between bulk and surface interactions and are therefore dependent on parameters such as particle size, host polarity and temperature.We used polar dispersion polymerization to create monodisperse polymer particles in the low micrometer range from a series of nematic monomers with lateral mesogen attachment. In this series of particles we observed a remarkable switch of the director configuration from bipolar to radial as a result of a small increase in the length of alkyl chains on the mesogen.A copolymerization study using mixtures of monomers which display bipolar or radial textures revealed a third confinement texture which was assigned as the twisted radial director configuration.Furthermore, we were able to observe a reversible switch in the director configuration in response to a change in the solvent polarity.In summary, our research reveals that the ordering in nematic polymer particles is influenced by subtle changes in the mesogen structure and that reversible ordering transitions are triggered by changes in the host environment. A clear change in the optical appearance of the particles is observed which provides a mechanism for sensor applications.

M3 - Abstract

T2 - 15th Topical Meeting on Optics of Liquid Crystals 2013

Y2 - 29 September 2013 through 4 October 2013

ER -