高电导率抗冻离子凝胶的制备及性能研究

Fabrication and Performance Research of Antifreeze Ionic Gels with High Conductivity

近年来,可穿戴设备在人体运动、身体体征以及体液检测等方面得到广泛应用。离子凝胶依靠其优异的离子导电性、热稳定性和电化学性能,广泛应用于柔性传感器,包括传感单元和柔性电极。大多数可穿戴传感器对低温条件的适应度不高,这阻碍了其在不同环境下的使用。鉴于此,本工作提出了一种高电导率抗冻离子凝胶,将丙烯酸(AA)、羧甲基纤维素钠(CMC)、丙烯酰胺(AAm)三种物质以AA与CMC,AA与AAm,AA、CMC和AAm三种组合相互形成共聚网络,并加入LiCl导电物质来制备一种在低温下依旧能保持良好电化学性能的离子凝胶。在三种类型的离子凝胶中,AA-CMC离子凝胶具有最高的电导率和对金属类器件表面最好的粘附性,对铁片的最大粘附力可达51.39 kPa,同时还具有优良的保湿抗冻功能(在25℃下7 d内失水率仅为4%以及-76℃的凝固点)和207.10%的断裂生长率。AA-CMC离子凝胶具有较好的导电性能(电导率最大为0.617 S/m)及柔软特性,可以组装成可穿戴柔性压力传感器;具有稳定的电化学性能且在长期在低温下也能保持自身的导电性能(-18℃冷冻3周电导率保持约原有的86.3%)。本工作所制备AA-CMC的离子凝胶将有望扩展其在柔性电子设备中的应用范围与使用前景。

In recent years,wearable devices have been widely used in human movement,physical signs and body fluid detection.Ionic gels are widely used in flexible sensors,including sensing units and flexible electrodes,because of their excellent ionic conductivity,thermal stability and electrochemical properties.Most wearable sensors are not well adapted to low temperature conditions,which hinders their use in different environments.In view of this,a high conductivity antifreeze ionic gel was proposed in this work.A copolymer network of acrylic acid(AA),sodium carboxymethyl cellulose(CMC)and acrylamide(AAm)was formed by the combination of AA and CMC,AA and AAm,AA,CMC and AAm,and LiCl conductive material was added to prepare an ionic gel that could maintain good electrochemical performance at low temperature.Among the three types of ion gels,AA-CMC ion gel has the highest electrical conductivity and the best adhesion to the surface of metal devices,and the maximum adhesion to iron sheets can reach 51.39 kPa.At the same time,it also has excellent moisturizing and antifreezing function(the water loss rate is only 4%within 7 days at 25℃and the freezing point of-76℃)and the fracture growth rate of 207.10%.The AA-CMC ionic gel has good electrical conductivity(up to 0.617 S/m),and can be assembled into a wearable flexible pressure sensor based on its soft properties.The electrochemical performance of the ionic gel is stable and can maintain its performance at low temperature for a long time(the conductivity of the ionic gel remains about 86.3%after freezing at-18℃for 3 weeks).The ionic gel(AA-CMC)prepared in this work is expected to expand its application range and application prospect in flexible electronic devices.