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Electro-induced orientational ordering of anisotropic pigment nanoparticles

DOI: 10.1098/rsta.2012.0257 DOI Help

Authors: Robert Greasty (University of Bristol) , Robert Richardson (University of Bristol) , Susanne Klein (HP Laboratories) , David Cherns (HH Wills Physics Laboratory) , Michael Thomas (University of Bristol) , Claire Pizzey (Diamond Light Source) , Nicholas Terrill (Diamond Light Source) , Cyrille Rochas (CERMAV-CNRS)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Philosophical Transactions Of The Royal Society A-mathematical Physical And Engineering Sciences

State: Published (Approved)
Published: March 2013

Abstract: The response of anisotropic pigment particle suspensions to externally applied electric fields has been explored for possible application in reflective display technologies. Three different types of pigment particle were suspended in dodecane, using a polymeric stabilizer, and showed Schlieren textures between crossed polarizers at high concentrations (greater than 25–30?wt%), indicating the formation of colloidal nematic phases. Orientational order parameters were determined by X-ray scattering, and the influence of polydispersity on the values is discussed. X-ray scattering measurements also demonstrated a change in the structure factor consistent with the onset of a colloidal nematic phase. In addition, the pigment particles were dispersed into various liquid crystal hosts at low concentrations (less than 5?wt%) with and without the presence of mesogenic mimic stabilizers. However, the influence of these stabilizers on orientational ordering could not be confirmed. The electro-induced ordering determined via scattering was related to the electro-optical response of each suspension using a simple model. The particles in nematic hosts not only showed a high degree of orientational ordering at lower electric field strengths, but also showed a reduction in stability. Although these systems have shown strong orientational ordering, the optical response has been limited by the intrinsic shape of the pigment particles and the distribution of the transition dipoles moments within them. Nevertheless, the feasibility of developing materials for display applications has been demonstrated.

Journal Keywords: Anisotropic Pigment Nanoparticles; Colloids; Liquid Crystals; X-Ray Scattering; Electric Field Alignment

Subject Areas: Chemistry


Instruments: I22-Small angle scattering & Diffraction