Effects of the preparing condition of a polymer-stabilised liquid crystal with a smectic-A−chiral nematic phase transition on its properties

Abstract

A homeotropically-oriented polymer network stabilised liquid crystal (PSLC) film with a smectic-A (SmA)–chiral nematic (N*) phase transition was prepared. In the temperature range of the SmA phase, the liquid crystal (LC) molecules were homeotropically oriented and the film showed a transparent state. However, in the temperature range of the N* phase, the film showed a strong light scattering state due to the LC molecules adopting a focal conic alignment affected by the homeotropically-oriented polymer network. Moreover, the strong light scattering state of the N* phase could return to the transparent state when an electric field is applied on it. The focus of this study is on the effects of the preparing conditions of the PSLC film, including the curing temperature and the intensity of the ultraviolet (UV) irradiation on its thermo-optical and electro-optical properties.

Keywords:

• smectic-A phase
• chiral nematic phase
• homeotropic polymer network
• electro-optical property
• thermo-optical property

Acknowledgements

Financial support from the Hi-tech Research and Development Program of China (Grant No. 2006AA03Z108), Program of Beijing Municipal Science and Technology (Grant No. Y045004040121) and Projects of Chinese National Science and Technology Tackling Key Problems (Grant No. 2006 BAI03A09) are gratefully acknowledged.