Liquid crystalline phases in suspensions of pigments in non-polar solvents

Susanne Klein*, Robert M. Richardson, Alexey Eremin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter in a book

Abstract

We will discuss colloid suspensions of pigments and compare their electro-optic properties with those of traditional dyed low molecular weight liquid crystal systems. There are several potential advantages of colloidal suspensions over low molecular weight liquid crystal systems: a very high contrast because of the high orientational order parameter of suspensions of rod shaped nano-particles, the excellent light fastness of pigments as compared to dyes and high colour saturations resulting from the high loading of the colour stuff. Although a weak 'single-particle' electro-optic response can be observed in dilute suspensions, the response is very much enhanced when the concentration of the particles is sufficient to lead to a nematic phase. Excellent stability of suspensions is beneficial for experimental observation and reproducibility, but it is a fundamental necessity for display applications. We therefore discuss a method to achieve long term stability of dispersed pigments and the reasons for its success. Small angle X-ray scattering was used to determine the orientational order parameter of the suspensions as a function of concentration and the dynamic response to an applied electric field. Optical properties were investigated for a wide range of pigment concentrations. Electro-optical phenomena, such as field-induced birefringence and switching, were characterised. In addition, mixtures of pigment suspensions with small amounts of ferro fluids show promise as future magneto-optical materials.

Original languageEnglish
Title of host publicationLiquid Crystals with Nano and Microparticles
PublisherWorld Scientific Publishing Co.
Pages847-870
Number of pages24
Volume2-2
ISBN (Electronic)9789814619264
ISBN (Print)9789814619257
DOIs
Publication statusPublished - 1 Jan 2016

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