含有偶氮苯结构单元的离子液体在智能材料中的应用与研究进展

Application and research progress of ionic liquids containing azobenzene moiety in smart materials

刺激响应性材料作为新型智能材料,在日常生活和工业生产方面有着重要应用,但能耗高、难以精准控制及循环可逆性差限制了其使用范围。偶氮苯基团是一种合成相对简单、循环可逆性好、易于精准控制、相对节能的光敏性官能团。离子液体是一类蒸汽压低、热稳定性好、可设计、对环境污染程度较低的新型液体材料。因此含有偶氮苯基团的离子液体是一类既具有光响应性,又具有离子液体特性的新型功能材料,凭借其在紫外/可见光(UV/Vis)照射下发生光致异构化,从而引起物化性质和材料性能发生可控变化,成为目前研究的热门。本工作综述了近年来含有偶氮苯基团的离子液体在光控智能材料中的应用,对含有偶氮苯结构单元的离子液体在光控电导率、光控自组装、光控相行为、光控CO的捕获与释放和光响应可控离子凝胶黏弹性等领域的研究进展进行了详细介绍,并对其未来的发展方向进行了展望。含有偶氮苯结构单元的离子液体具有独特的优势,在可持续发展的大背景下能够为智能材料、绿色化学的发展提供新的思路。

As a new type of smart material, stimuli-responsive materials have many important applications both in daily life and industrial production. However, such materials are just applied in limited fields because of high energy consumption, difficulty in precise control, and poor cycle reversibility. Azobenzene compound, where there is a photosensitive functional group, is relatively simple to be synthesized. And they are of good cycle reversibility, easy precise control, and relatively energy saving. The ionic liquid that exists as the liquid is a new type of material with low vapor pressure, good thermal stability, and low pollution to the environment. Moreover, the structure of ionic liquid is designable. Therefore, ionic liquid containing an azobenzene moiety is a new type of functional material that exhibits dual characteristics as light stimuli-responsiveness and ionic liquids. Taking full advantage of the photoisomerization which is induced by ultraviolet and visible light irradiation, the physical and chemical properties of such materials can be tuned. The issue of light stimuli-responsive ionic liquids containing azobenzene moieties has been a hot topic in recent years. This article reviewed and summarized recent studies on the properties and performance of ionic liquids containing azobenzene group upon UV and visible light irradiation, which was furtherly applied in the field of smart materials. Specifically, examples of recent applications of ionic liquids containing azobenzene group across a multitude of fields such as light-controlled conductivity, light-controlled self-assembly,light-controlled phase behavior, light-controlled COcapture and release as well as light response controllable viscoelasticity of ionic gel are all described in detail, and their future development also prospects in this work. Ionic liquids containing azobenzene moiety have unique advantages and are expected to provide new ideas for the development of smart materials and green chemistry under the background of sustainable development.