基于光驱动分子马达的新型智能液晶材料

Recently the development of synthetic systems that are stimuli-responsive and capable of converting molecular motion into macroscopic movement becomes an important research topic in field of molecular machines. The use of a non-invasive light stimulus to induce motion with high spatial-temporal precision affords ample light-responsive materials and most of them are based on molecular switches. As molecular switches usually have two states, which cannot drive the whole system out-of-equilibrium, it largely hinders the complex function of light-responsive materials. Instead, light-driven molecular motors displays continuous unidirectional rotation upon light irradiation, which makes them distinct from traditional molecular switches. This proposal aims at design and synthesis of a series of light-driven molecular motors and further construction of them covalently into polymeric liquid crystals. Through the well-aligned liquid crystals network, the light-induced unidirectional rotation of molecular motors can be amplified via cooperative interactions along many length scales in order to sustain a macroscopic mechanical motion. We screen the most reliable light-responsive materials with the best efficient and further convert them into devices. This proposal is a challenge in field of molecular machines and will lay a solid foundation for novel dynamic light-responsive materials.

近年来，分子机器领域中的一个重要的研究热点，就是如何将受控的分子运动，放大并转变为宏观材料的动态性能的改变。以光信号作为调控手段的智能材料，由于其响应时间短，可被精准调控，无废弃物，得到了广泛的关注。然而，目前大部分报道的光响应材料均以光控分子开关为基础，由于分子开关往往仅有两种简单的状态，因而使得整个体系无法达到远离平衡态，从而限制了光响应材料的进一步发展。本项目拟设计与合成一系列光驱动的分子马达，并将其共价键合于液晶材料中。由此，利用液晶材料的有序性，将分子马达分子层面的运动，通过协同放大效应，转变为材料宏观性质的改变。由于分子马达的单向连续转动，将使得体系能远离平衡态，从而实现多重甚至更为复杂的功能调控。本项目拟筛选出光响应性能较好的一批材料，进一步对其进行器件集成化测试，为新型光响应智能材料的实际应用打下良好的基础。

本项目将光响应定向转动的分子马达通过共价键合，构筑于有序的液晶网络中，从而制得一批新型的响应型液晶智能材料。整体研究按计划有序地展开，制备了一系列新型的分子马达，分子马达的核心结构为位于分子中间的大位阻双键。分子马达的上下两端通过化学修饰的方法，引入不同长度的柔性脂肪链作为连接单元。长的柔性链能够提供足够的空间，以供分子马达在液晶中进行转动。在长链末尾，预留末端双键，用于与液晶材料的进行共聚反应。得到一系列功能化的外消旋分子马达后，我们利用手性色谱柱，把分子马达拆分成光学纯的异构体，并分别把外消旋分子马达和光学纯分子马达构筑到液晶网络中，制备成光响应型液晶材料。所得的液晶薄膜，能够产生快速的光响应摆动，在表面上移动，并且能够完成单向的左旋或右旋扭动，为制备复杂的软物质材料奠定了重要的基础。