The kinetics of photo-polymerisation in the fabrication of polymer-dispersed liquid crystals doped with nano-graphite

Abstract

It is known that the electro-optical behaviour of polymer-dispersed liquid crystals depends on the separation of the polymer and liquid crystal phases. The morphology of the liquid crystal domains depends on the nature of the chemical and physical processes occurring during domain formation. This work discusses the two-phase morphology found in an acrylate-based system that develops during polymerisation-induced phase separation. The effect of the dopant nano-graphite on the polymerisation and electro-optical properties are discussed. UV/VIS and time-resolved Fourier transform infrared spectroscopy is used for monitoring the polymerisation of the polymer-dispersed liquid crystals. The electro-optical properties of the polymer-dispersed liquid crystal films are measured using a polarimeter (PerkinElmer Model 341). The morphology of the liquid crystal droplets in the polymer matrix is probed by polarising optical microscopy and Fourier transform infrared spectroscopy images. The threshold voltage of the polymer-dispersed liquid crystals is dramatically decreased because of the increased conductivity of the polymer matrix on doping by nano-graphite.

Keywords:

• kinetic photo-polymerisation
• real-time transmittance
• electrooptical
• FTIR images
• morphology

Acknowledgments

The authors are grateful to National Science Fundamental Committee of China, HI-Tech Research and development program (863), the commission for science, technology and industry for national defence (DBDX2008038) of China.