Abstract:

The construction of multifunctional hydrogel flexible sensors with excellent conductivity and multiple shape memory is extremely challenging. Herein, MXene nanosheets were incorporated into both temperature-responsive polymer polyvinyl alcohol and metal ion-responsive polyacrylic acid networks by free copolymerization and freeze-thaw methods through molecular design to prepare a conductive hydrogel with dual shape memory and construct a strain sensor. The morphology and structure of MXene nanosheets and composite hydrogels were studied by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and infrared spectroscopy, and the influence of MXene content on the mechanical properties, electrical conductivity and shape memory performance of the hydrogels were investigated. The research shows that MXene nanosheets uniformly dispersed in the hydrogel and crosslinked with the hydrogel network through hydrogen bonding, which not only strengthens the mechanical properties of the hydrogel, but also improves the shape fixation rate of the double shape memory hydrogel. The tensile strength of the composite hydrogel is increased to 236.10 kPa, 7.3 times that of the pure water gel, the shape fixation rate of ferric ions increased from 69.44% to 94.44%, and the shape fixation rate of the temperature response increased from 63.89% to 88.89%. The signal of the hydrogel sensor showed excellent continuity and consistency under multiple rapid tensile strain cycles, which provides new ideas for the construction of environmentally adaptive flexible sensors.

Key words: polymer, nanomaterials, gels, flexible sensor, mechanical properties

摘要：

兼具优良导电性和多重形状记忆多功能水凝胶柔性传感器的构筑极具挑战。通过分子设计采用自由共聚和冷冻-解冻法将MXene纳米片引入兼具温度响应的高分子聚乙烯醇和金属离子响应的聚丙烯酸网络中，制备了具有双重形状记忆的导电水凝胶并构筑了应变传感器。采用透射电镜、扫描电镜、X射线衍射及傅里叶红外光谱等技术研究了该纳米片和复合水凝胶的形貌及结构，研究了MXene含量对该水凝胶力学性能、导电性能及形状记忆性能的影响规律。研究表明：MXene纳米片均匀分散在复合水凝胶中，且与水凝胶网络通过氢键交联，这不仅强化了该水凝胶的力学性能，而且提高了双重形状记性水凝胶的形状固定率。其中，复合水凝胶的抗拉强度提升至236.10 kPa，是纯水凝胶的7.3倍，对铁离子的形状固定率从69.44%增加至94.44%，对温度响应的形状固定率从63.89%增加至88.89％。该水凝胶传感器的信号在多次快速拉伸应变循环下表现出色的连续性和一致性，这为环境适应性柔性传感器的构筑提供了新思路。

关键词: 聚合物, 纳米材料, 凝胶, 柔性传感器, 力学性能