基于离子液体和二芳基乙烯的离子凝胶的光致变色、导电、自修复及柔性传感性能

Ionic Gels Based on Ionic Liquids and Diaryl Ethylene:Photochromic,Conductive,Self-Healing,and Flexible Sensing Properties

在丙烯酸聚合中原位引入4,4'‑(全氟环戊烯‑1,2‑二基)双(5‑甲基噻吩‑2‑甲醛)(DEA)和离子液体1‑丁基‑3‑甲基咪唑四氟硼酸盐((BMIm)BF_(4)),制备了一种同时具有光致变色、导电、自黏附且具有宽温度工作区间等性能的新型离子自修复凝胶DPZI。由于(BMIm)BF_(4)的高热稳定性和低蒸气压,所获得的DPZI凝胶在-20~40℃较宽的温度下表现出高度稳定的机械和离子导电性能。DPZI系统中引入的Zn^(2+)与—COO^(-)形成动态配位键,使得凝胶具有快速的自修复能力,0.06 s即可超快恢复电阻响应;离子液体的引入同时赋予了凝胶优异的抗冻性。DPZI因光致变色单元DEA的异构化可在10 s内快速发生黄-蓝颜色可逆转变,且光致变色单元的开环/闭环异构化能够实现对凝胶导电性的调节。此外,DPZI凝胶应变/压力式传感器可迅速、精准感知人体不同部位的运动并做出相应的响应;也可对呼吸、心率、声音做出精准识别,应变灵敏度为0.2%。

It remains a challenge in the preparation of multifunctional conductive gels which combine self‑healing and the ability to respond to complex environments.In this work,a new ionic self‑healing gel DPZI with the properties of photochromic,conductive,self‑adhesive,and wide temperature working range was prepared by polymerization of acrylic acid with the addition of 4,4'‑(perfluorocyclopentene‑1,2‑diyl)bis(5‑methylthiophene‑2‑carbaldehyde)(DEA)and 1‑butyl‑3‑methylimidazolium tetrafluoroborate((BMIm)BF_(4))ionic liquids.Owing to the high thermal stability and low vapor pressure of(BMIm)BF_(4),the obtained DPZI gel exhibited good mechanical properties in a wide temperature range from-20 to 40℃and high ionic conductivity.The dynamic coordination bond formed by Zn^(2+) and—COO^(-) introduced in the DPZI system enabled the gel to possess rapid self‑healing ability and ultra‑fast resistive response recovery in 0.06 s.The gel displayed excellent anti‑freezing properties due to the combination of ionic liquids.DPZI exhibited a rapid reversible yellow‑blue color transition within 10 s due to the isomerization of the photochromic unit DEA,and the open‑loop form/closed‑loop form isomerization of the photochromic unit also enabled the regulation of gel conductivity.Additionally,it showed good cycling stability with minor resistance fluctuations over 50 stretch‑release cycles.Given its superior performance,the DPZI gel could effectively detect and distinguish human motions,such as the bending and stretching of a finger,knee,neck,or elbow joint,with a rapid and reliable signal response(strain sensitivity of 0.2%).