一种光学状态可由电场控制的液晶复合材料的制备与表征

液晶材料对电、热、磁、光等外界物理量的变化具有不同的响应特性,向其中添加具有一定特性的化合物,可以得到具备一定响应特性的液晶复合材料。利用所制备的液晶复合材料对于电场变化具有响应特性的特点,制备出具有信息记录功能的复合材料。合成手性离子液体,按一定配比将其加入手征向列相液晶(N~*-LC)中,得到反射波段可电控的手征向列相液晶/手性离子液体复合材料。实验结果表明:材料初始状态为光透射状态;对材料施加直流电压40V时,样品表现为光散射状态,透过率低于10%;施加高频交流电压40V时,样品表现为半透明镜面反射,反射范围覆盖400～750nm,透射率为45%左右;撤去电场后,可恢复至初始状态,并且每种状态都具有一定的记忆效应。该种液晶复合材料制备简单,无需紫外辐射工艺,且具有电场响应特性,可以通过电场控制在可见光范围内表现出光透射、强烈光散射、半透明镜面反射3种不同状态,具有记忆效应,操作简单方便。

Preparation and characterization of liquid crystal composite material with electrically controlled optical states

Liquid crystal materials provide different responses to changes of external physical quantities, such as electric field, heat, magnetic field and light, and liquid crystal composites with certain response characteristics can be prepared by adding compounds with certain properties. Composite materials with information recording function can be prepared based on the prepared liquid crystal composites with responses to electric field changes. Chiral ionic liquid was synthesized. By proportionally adding the sythesized chiral ionic liquid into N^*-LC, an N^*-LC/chiral ionic liquid composite material was obtained, whose reflective wavelengths were electrically controlled. Experimental results indicate that the prepared N^*-LC/chiral ionic liquid composite material is in an original light-transmitting state. When a direct voltage of 40 V is applied, the material is switched to a light-scattering state with a light transmittance being less than 40%. When a high-frequency alternating voltage of 40 V is applied, the material is switched into a semitransparent mirror reflecting state with a reflecting range of 400~750 nm and a light transmittance being about 45%. When the electric field is removed, the material recovers to the original state, and all these states can be memorized for some time. The liquid crystal composite material can be prepared easily without UV radiation process. The liquid crystal composite material has response characteristics to electric field, and can be electrically switched among three different states of light transmission, strong light scattering and semitransparent mirror reflection within a visible-light wavelength range. The liquid crystal composite material also has memory effect, and the switching operation is easy and convenient.