Zhu Xueling, Han Kai, Li Chao, Wang Jianlong, Yuan Jinfeng, Pan Zhicheng, Pan Mingwang
Department of Polymer Materials and Engineering, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, P. R. China.
Hebei Key Laboratory of Functional Polymers, Hebei University of Technology, Tianjin 300401, P. R. China.
ACS Appl Mater Interfaces. 2023 Apr 19;15(15):19414-19426. doi: 10.1021/acsami.3c00333. Epub 2023 Apr 5.
Polymers that integrate multiple functions into one system broaden the application range of materials, but it remains a great challenge to obtain polymer materials with simultaneously high strength, high toughness, and high self-healing rate. In this work, we prepared waterborne polyurethane (WPU) elastomers using Schiff bases containing disulfide and acylhydrazone bonds (PD) as chain extenders. Acylhydrazone forming a hydrogen bond not only acts as a physical cross-linking point, which promotes the microphase separation of polyurethane to increase the thermal stability, tensile strength, and toughness of the elastomer, but also serves as a "clip" to integrate various dynamic bonds together to synergistically reduce the activation energy of the polymer chain movement and endow the molecular chain with faster fluidity. Therefore, WPU-PD exhibits excellent mechanical properties at room temperature, such as a tensile strength and a fracture energy of 25.91 MPa and 121.66 kJ m, respectively, and a high self-healing efficiency of 93.7% in a short time under moderate heating conditions. In addition, the photoluminescence property of WPU-PD enables us to track its self-healing process by monitoring change of the fluorescence intensity at the cracks, which helps to avoid the accumulation of cracks and improve the reliability of the elastomer. This self-healing polyurethane has a great potential application value in optical anticounterfeiting, flexible electronics devices, functional automobile protective films, and so on.
将多种功能集成于一个体系的聚合物拓宽了材料的应用范围，但要获得同时具有高强度、高韧性和高自愈率的聚合物材料仍然是一个巨大的挑战。在这项工作中，我们使用含有二硫键和酰腙键（PD）的席夫碱作为扩链剂制备了水性聚氨酯（WPU）弹性体。形成氢键的酰腙不仅作为物理交联点，促进聚氨酯的微相分离以提高弹性体的热稳定性、拉伸强度和韧性，还作为“夹子”将各种动态键整合在一起，协同降低聚合物链运动的活化能，赋予分子链更快的流动性。因此，WPU-PD在室温下表现出优异的力学性能，例如拉伸强度和断裂能分别为25.91 MPa和121.66 kJ m，并且在适度加热条件下短时间内具有93.7%的高自愈效率。此外，WPU-PD的光致发光特性使我们能够通过监测裂纹处荧光强度的变化来跟踪其自愈过程，这有助于避免裂纹的积累并提高弹性体的可靠性。这种自愈型聚氨酯在光学防伪、柔性电子器件、功能性汽车保护膜等方面具有巨大的潜在应用价值。
