Low-temperature properties of polymer-stabilised liquid-crystal blue phases

The temperature dependences of the Kerr coefficient and the response time in the electrooptical effect of polymer-stabilised blue phases (PSBPs) of liquid crystals (LCs) with various polymer concentrations are investigated in a wide temperature range including temperatures lower than room temperature. The Kerr coefficients are found to abruptly decrease at low temperature, and the response time-temperature relation obeys the Arrhenius equation. For comparison of the Kerr effect and molecular rotation at low temperature, various physical properties such as permittivity, rotational relaxation time and dielectric relaxation strength of the PSBPs are investigated. The electrooptical response times and the dielectric relaxation times show different temperature dependences, and rotation of LC molecules in PSBPs was sufficiently active at low temperature and not strongly affected by the polymer. Hierarchical dynamics of polymer-stabilised blue phases are studied by means of dielectric relaxation time and electrooptical response, which showed different temperature dependences obeying the Vogel-Fulcher and Arrhenius equations (the picture shows the Arrhenius relations). The polymer concentration affects the electrooptical effect but not the rotation of the LC molecules in PSBPs.