Abstract:

Recently, the conductive hydrogels have attracted increasing attention because of the applications in various fields, including electronic drivers, medical monitoring sensors, and wearable devices etc. However, most hydrogels suffer from low mechanical properties, short service life, and poor frost resistance, which limit the applications in low-temperature. To solve this problem, the present work fabricated the self-healable and low temperature resistant multifunctional ionic hydrogel used for strain sensors, where poly(vinyl alcohol), ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), and phytic acid were used as the raw materials, which were dissolved in deionized water and dimethyl sulfoxide (DMSO) binary solution. The mixed polymer solution spontaneously transferred into ion hydrogel with the help of supramolecular self-assembly caused by the multiple hydrogen bonds and electrostatic interactions between ionic groups. At the same time, adjusting the content of DMSO can optimize the strength and toughness of the gel. When the DMSO volume fraction is 40%, the maximum tensile strength and elongation at break can reach 4.43 MPa and 869.1% respectively. The microstructure, thermal and mechanical properties of the ionic hydrogel were carried out by scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, tensile testing, and rheological test. The results showed that the hydrogel had outstanding mechanical properties, rapid self-healing ability, and exceptional redox driven shape memory effect. The hydrogel could maintain high elasticity, conductivity, and sensitivity for strain sensing even at -25℃. In addition, the piezoresistive sensing performance of the gel sensors was tested by using electrochemical methods to accurately detect large-scale and subtle human behaviors by monitoring the real-time current change. The materials (PVA, PA, and IL) used in the hydrogel possess unique advantages, such as non-toxicity and high biocompatibility. The safety, biocompatibility and frost resistance of the ionic hydrogel enhance the potential applications in the fields of low-temperature strain sensors, intelligent wearable responsive components, and soft robotics.

Key words: ionic liquids, gels, polymers, poly(vinyl alcohol), self-healing, anti-freezing, strain sensor

摘要：

近年来，导电水凝胶在电子驱动器、医疗监测传感器及可穿戴设备等领域的应用备受关注。然而，多数凝胶机械强度低、寿命短、抗冻性能差，从而导致低温下无法使用。为了解决该问题，以聚乙烯醇、离子液体1-丁基-3-甲基咪唑四氟硼酸盐和植酸为原料，在水与二甲基亚砜（DMSO）二元溶液中借助多重氢键及离子基团间的静电作用实现了超分子自组装，制备出一种可用于应变传感的自愈合、耐低温多功能离子水凝胶。研究发现在凝胶中引入DMSO，凝胶表现出优异的抗冻能力；同时，调节DMSO的含量可优化凝胶的强度和韧性，当DMSO体积分数为40%时，最大拉伸强度和断裂伸长率分别可达4.43 MPa和869.1%。该离子水凝胶在低温应变传感器、智能可穿戴响应元件等领域展现出较好的应用潜力。

关键词: 离子液体, 凝胶, 聚合物, 聚乙烯醇, 自愈合, 抗冻, 应变传感器