Effect of Different Dopants on Polymer Cholesteric Liquid Crystal Flakes

Abstract

Two types of dopants are incorporated into polymer cholesteric liquid crystal (PCLC) materials to change their dielectric properties. Conductive dopants consisting of either carbon-based or metallic particles show large increases in composite conductivity with percolation thresholds of from 0.4 vol% to 30 vol%, depending on the size and shape of the dopant particles. Inorganic insulating dopants change the dielectric constant from 2 (neat PCLC) to < 10 at dopant levels of ∼ 30 vol%, accompanied by an increase in density. These composites offer opportunities for use of PCLC's as particles or flakes in reflective displays.

Keywords:

• conductivity
• dielectric constant
• dopants
• particle displays
• percolation threshold
• polymer cholesteric liquid crystals

Acknowledgments

The authors thank K. L. Marshall and Dr. T. Z. Kosc (Laboratory for Laser Energetics) for suggestions regarding this manuscript. The authors also acknowledge K. Hasman and Jessica DeGroote (The Institute of Optics, University of Rochester) for sample preparation and the acquisition of SEM images, respectively. Author ATP acknowledges the Laboratory for Laser Energetics at the University of Rochester for Horton Fellowship support.

Notes

*Primary average particle dimensions.