Liu Tong, Li ChuanLong, Yao Hai, Sun FuYao, Wang Lin, Yao BoWen, Xu JianHua, Fu JiaJun
School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Joint Laboratory of Advanced Biomedical Materials (NFU-UGent), College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
Mater Horiz. 2023 Jul 31;10(8):2968-2979. doi: 10.1039/d3mh00358b.
Soft self-healing materials are crucial for the development of next-generation wearable electronics that could function in dynamic environments and resist mechanical damage. However, several challenges remain, including fatigue fracture, poor elasticity, and thermodynamic lability, which significantly limit their practical applications. Here, with a model system of soft self-healing polyurea, we propose a molecular engineering strategy of transforming inherently fragile materials with an island-like structure into resilient ones with a bicontinuous nanophase separation structure using 2-ureido-4-pyrimidinone (UPy) supramolecular motifs as structural regulators. The dynamic and continuous hard domains modified by UPy formed a repairable bicontinuous network similar to those of the reticular layer in animal dermis. This design allows for a simultaneous and tremendous improvement in the fatigue threshold (34.8-fold increase), elastic restorability (the maximum elongation for full dimensional recovery increasing from 6 times to 13 times), and thermodynamic stability (4 orders of magnitude improvement in the characteristic flow transition relaxation time), without significantly compromising the compliance, autonomous self-healing, and optical transparency. These mechanical and thermodynamic improvements address current limitations in unfilled soft self-healing materials as reliable substrates for transparent strain-electronics.
柔软的自修复材料对于下一代可穿戴电子产品的发展至关重要，这些产品能够在动态环境中发挥作用并抵抗机械损伤。然而，仍然存在一些挑战，包括疲劳断裂、弹性差和热力学不稳定性，这显著限制了它们的实际应用。在此，通过一个柔软自修复聚脲的模型体系，我们提出了一种分子工程策略，即使用2-脲基-4-嘧啶酮（UPy）超分子基序作为结构调节剂，将具有岛状结构的固有脆性材料转变为具有双连续纳米相分离结构的弹性材料。由UPy修饰的动态且连续的硬域形成了一个可修复的双连续网络，类似于动物真皮中的网状层。这种设计能够同时大幅提高疲劳阈值（提高34.8倍）、弹性恢复能力（完全尺寸恢复的最大伸长率从6倍增加到13倍）和热力学稳定性（特征流动转变弛豫时间提高4个数量级），而不会显著损害柔韧性、自主自修复能力和光学透明度。这些机械和热力学方面的改进解决了未填充的柔软自修复材料作为透明应变电子器件可靠基底的当前局限性。
