超声对纤维素纳米晶体的溶致胆甾相液晶的影响

摘要

The ultrasonic effect on the lyotropic chiral nematic liquid crystal (N∗-LC)of cellulose nanocrystal(CNC)and optical properties of the solid N∗-LC film were investigated by using polarized light microscopy(POM),UV-visible spectroscopy(UV-vis),X-ray diffraction(XRD)analysis,and electric conductivity,etc.It is found that the pitch of the N∗-LC was stretched with the increase of the ultrasonic power.The reflection wave length of the N∗-LC solid film was red-shifted with the in-crease of the ultrasonic power.The amplitude of the red-shift of reflection wave length depended on the applied ultrasonic power.The conductivity of the lyotropic N∗-LC increased after ultrasound treatment.As a consequence,it is speculated that the high power ultrasonic treatment releases some of the ions trapped in the bounded electric double layer on the surface of CNC particles,which make the electrostatic repulsion between CNC increasing.So the increase in the repulsion force resulted in a larger pitch and a red-shift of the iridescence wavelength of the resulting solid film.%通过偏光显微镜法、紫外-可见光光谱学、XRD 和电导率分析方法研究了大功率超声对纤维素纳米晶体(CNC)的溶致胆甾相液晶(N∗-LC)螺距的影响及其在干燥状态下所制得薄膜的光学性能。研究结果表明,溶致 N∗-LC 的螺距随着超声功率的增大而增大,其干燥薄膜的反射波波长红移,且红移幅度与超声功率有关。但是,CNC 的晶型和尺寸没有明显变化。电导率测试结果表明,超声处理使溶致 N∗-LC 的电导率提高。由此推测溶致 N∗-LC 的螺距增大的主要原因是大功率超声处理使束缚在双电层中的带电离子释放出来,进而 CNC 粒子之间的静电斥力变大所致。