Polymer-stabilized fast-relaxation dye-doped cholesteric liquid crystals with a wide temperature range by thiol-Michael addition polymerization

Abstract

The transient planar (TP) state during the relaxation process, from homeotropic (H) to planar (P) state, of dye-doped cholesteric liquid crystals (DDCLCs) can be eliminated by adjusting the elastic constants, reducing the time and haze of the relaxation process. However, the elastic constants are easily influenced by temperature. Therefore, the operating temperature range for fast-relaxation DDCLCs is relatively narrow. This work demonstrates that a polymer helical template can be formed in the P state of DDCLCs by thiol-Michael addition polymerization. It can significantly expand the temperature range from 20 °C to 60 °C for fast-relaxation DDCLCs. More importantly, polymer-stabilized dye-doped cholesteric liquid crystals (PS-DDCLCs) did not show any reduction in the absorption of the dye or discoloration after polymerization. PS-DDCLCs could still achieve tri-state switching and could be used for fast-relaxation smart windows capable of adapting to increasing environmental temperatures. The proposed smart window can be used in vehicles and aircraft to prevent glare and protect privacy.