刺激响应性胆甾型液晶软光子彩膜

Stimuli-responsive cholesteric liquid crystal soft photonic color film

为实现软光子晶体图案的多重信息加密或存储,本文基于硫醇-丙烯酸酯Michael加成和光聚合反应设计并制备了一种刺激响应性胆甾型液晶(cholesteric liquid crystal,CLC)软光子彩膜。首先,通过改变反应混合物中手性剂的比重调节初始彩膜结构色;其次,用小分子液晶稀释液晶前聚体;最后,通过紫外光固化对单层软光子彩膜进行交联密度的时间编程,同时借助掩膜曝光技术对其纳米结构进行空间编程。实验结果表明,虽然在超600 min的反应过程中软光子彩膜的布拉格反射中心波长仅移动了19 nm,但是通过时间-空间双重编程局部修改其变色响应,可使带有隐形图案的软光子薄膜在应力作用下逐渐呈现从红到绿的多彩外观,反射波长覆盖范围超过100 nm。这种刺激响应性软光子彩膜在光子晶体图案的动态显示、防伪、信息存储等领域具有重要的应用价值。

In order to realize multiple information encryption or storage of soft photonic crystal patterns,a stimuli-responsive cholesteric liquid crystal(CLC)soft photonic color film is designed and fabricated based on the thiol-acrylate Michael addition and photopolymerization reaction.First,the initial color of the reaction mixture is adjusted by changing the ratio of the doping chiral agent.Then small molecule liquid crystal is added into the mixture to adjust its viscosity.Finally,the temporal programming of the cross-linking density of the CLC soft photonic color film is carried out by ultraviolet(UV)exposure at different stages of the reaction,and the spatial programming is performed cooperatively with the help of photomasks.The experimental results indicate that the Bragg reflection wavelength of the CLC film only moves 19 nm during the reaction process of over 600 min.However,by locally modifying its color response via spatio-temporally dual-programming,the soft photonic film with invisible patterns can be made to gradually take on a colorful appearance from red to green with stretching,and reflected wavelength coverage over 100 nm.This stimuliresponsive soft photonic color film can be employed for the dynamic display of photonic crystal patterns,and is potentially useful for multiple anti-counterfeiting or information storage.