防伪用胆甾相液晶复合材料的可控制备与性能研究

Nowadays, the structural design and controllable preparation of the light, electricity, and magnetic information functional materials has become a major concern. Due to their unique ability to self-organize into a helical supramolecular architecture and their excellent selective reflection of light based on the Bragg relationship, cholesteric liquid crystals have great application prospects in the field of anti-counterfeiting, information storage, etc. This project is to design the molecular structure of the liquid crystal materials, a series of side chain liquid crystal polymer (SCLCP) with cholesteric phase (Ch) and smectic A (SmA)-Ch characteristics, as well as chiral compounds by light regulation will be designed and synthesized, respectively. Then, they will be mixed with chiral compounds, nematic liquid crystals, and fluorescent nanoparticles, to explore the preparation of liquid crystal materials with stable Ch, SmA - Ch transition features. Their molecular design and synthetic methods, condensed structures and the behaviors of the phase transition, as well as the precise regulation of their pitches of the Ch liquid crystals will be systematically studied. The relationship between the light reflection characteristics of the LC materials and the interaction mechanism between the various compounds will be elucidated, so as to obtain the LC composite materials with features of discoloration by angle and temperature changes as well as photochromic properties, and to provide experimental foundation and theoretical guidance for the development of LC composite materials with multiple anti-counterfeiting characteristics.

近年来，以功能为导向的光、电、磁信息功能材料的结构设计和可控制备备受关注。胆甾相液晶由于其独特的自组装形成超分子螺旋结构的能力及选择性光反射特性，是一类在防伪、信息存储等领域具有巨大应用前景的软物质材料。本项目拟对液晶材料的分子结构进行设计，通过制备具有胆甾相（Ch）、近晶A（SmA）-Ch转变的侧链高分子液晶（SCLCP）及光调控手性化合物，将其与手性化合物、向列相液晶等共混，探索制备具有稳定Ch、SmA-Ch转变的液晶复合材料。系统研究Ch、SmA-Ch转变的SCLCP、光调控手性化合物等材料的分子设计与合成方法，液晶复合材料的凝聚态结构、相转变温度、胆甾相液晶的螺距等的精确调控方法，阐明液晶材料的光反射特性与分子结构之间的关系，揭示复合材料中各组分间的相互作用机制，最终获得具有角异和温敏变色及光致变色特性的液晶复合材料，从而为开发具有多重防伪特性的液晶复合材料提供实验数据和理论指导。

本项目设计合成了系列具有向列相、近晶相、胆甾相和近晶-胆甾相转变的侧链高分子液晶材料，详细研究了材料的液晶相转变行为及光学特性。通过液晶材料的混配，利用胆甾相液晶材料制备了具有角异变色特性的侧链高分子液晶复合薄膜，实现了材料的一线防伪；利用近晶-胆甾相转变且相转变温度可调的侧链高分子液晶复合材料制备了温敏变色特性的侧链高分子液晶复合薄膜，实现了材料的二线防伪；通过向液晶材料中引入聚合物网络，为防伪薄膜增加了特异性识别特征，实现了材料的三线防伪；通过向胆甾相液晶材料中引入量子点，利用不同温度下胆甾相液晶材料的选择性反射波长和量子点荧光发射光谱之间相对位置的不同导致的荧光发射波谱的变化或观察到的荧光图案的不同，在同一材料中实现了多重防伪特性。