Key Laboratory of Functional Polymer Materials, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, P. R. China.
Mater Horiz. 2022 Nov 28;9(12):3057-3069. doi: 10.1039/d2mh00456a.
Conductive hydrogels are excellent candidates for the next-generation wearable materials and are being extensively investigated for their potential use in health monitoring devices, human-machine interfaces, and other fields. However, their relatively low mechanical strength and performance degradation due to swelling have presented challenges in their practical application. Inspired by the multiscale heterogeneous architecture of biological tissue, a dynamic cross-linked, ultra-tough, and high-sensitivity hydrogel with a swelling resistance characteristic was fabricated by the principle of multiple non-covalent interaction matching and a step-by-step construction strategy. A heterogeneous structure was constructed by the combination of a 'soft' hydrophobic-conjugated micro-region structural domain with inter/intra-molecular hydrogen bonding and π-π stacking along with 'rigid' cross-linking strong ionic coordination interactions. Reversible cross-linking synergies and variations in the content of rigid and flexible components guaranteed the hydrogel to undergo flexible and efficient modulation of the structures and gain excellent mechanics, including elongation at break (>2000%), toughness (∼60 MJ m), and recovery (>88%). Notably, hydrogels displayed good anti-swelling properties even in solutions with different pH (pH 2-11) and solvents. Moreover, the hydrogel further exhibited fast response (47.4 ms) and high sensitivity due to the presence of dynamic ions (Fe, Na, and Cl); therefore, it was assembled into a sensor to detect various human motions and used as a signal transmitter for the encryption and decryption of information according to Morse code. This study provides basis for the development of a variety of robust and flexible conductive hydrogels with multifunctional sensing applications in next-generation wearable devices.
导电水凝胶是下一代可穿戴材料的优秀候选材料，由于其在健康监测设备、人机界面和其他领域的潜在应用而受到广泛研究。然而，它们相对较低的机械强度和由于溶胀导致的性能下降在实际应用中带来了挑战。受生物组织多尺度异质结构的启发，通过多种非共价相互作用匹配和逐步构建策略的原理，制备了一种具有抗溶胀特性的动态交联、超坚韧和高灵敏度水凝胶。通过将“软”疏水性共轭微区结构域与分子间/内氢键和π-π堆积与“硬”交联强离子配位相互作用结合，构建了一种非均质结构。可逆交联协同作用和刚性和柔性成分含量的变化保证了水凝胶能够灵活有效地调节结构，并获得优异的力学性能，包括断裂伸长率（>2000%）、韧性（~60 MJ m）和恢复率（>88%）。值得注意的是，水凝胶即使在不同 pH（pH 2-11）和溶剂的溶液中也表现出良好的抗溶胀性能。此外，由于动态离子（Fe、Na 和 Cl）的存在，水凝胶进一步表现出快速响应（47.4 ms）和高灵敏度；因此，它被组装成传感器来检测各种人体运动，并用作根据莫尔斯电码加密和解密信息的信号发射器。这项研究为开发各种具有多功能传感应用的坚固灵活的导电水凝胶提供了基础，可用于下一代可穿戴设备。
