Yin Haiyan, You Min, Shi Xinlei, Yu Hui, Chen Qiang
Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, 352001, Zhejiang, China.
Joint Research Center of Medicine, The Affiliated Xiangshan Hospital of Wenzhou Medical University, Ningbo, Zhejiang 315700, China.
Mater Horiz. 2024 Aug 12;11(16):3946-3960. doi: 10.1039/d4mh00164h.
Zwitterionic hydrogels are electrically neutral materials with both cationic and anionic groups that impart excellent anti-fouling properties and ion channel orientations. However, pure zwitterionic hydrogels generally exhibit low strength and toughness. In this study, it has been discovered that polymerizable zwitterionic monomers in aqueous solution exhibit a unique liquid-liquid phase separation phenomenon at a high monomer concentration of ≥50 wt%, resulting in pure and commercial zwitterionic hydrogels with high compressive strength (6.5 MPa) and high toughness (2.12 kJ m). This phase separation and the corresponding aggregations might be caused by strong dipole-dipole interactions among residual zwitterionic monomers under the lack of free-water condition. The synergistic effect of liquid-liquid phase separation and polymer entanglement enhances the mechanical strength, toughness, self-recovery, and anti-freezing properties of pure polyzwitterionic hydrogels. Moreover, the high fracture energy of highly elongated yet tough polyzwitterionic hydrogels facilitates the development of high crack propagation resistance, which supports an expanded role in tissue engineering, soft flexible devices, and electronics applications with improved durability. A wide range of applications for the proposed polyzwitterionic hydrogels is demonstrated by the development and testing of a strain sensor and a triboelectric nanogenerator device. Our findings provide novel insights into the network structure of pure polyzwitterionic hydrogels.
两性离子水凝胶是带有阳离子和阴离子基团的电中性材料，具有出色的抗污性能和离子通道取向。然而，纯两性离子水凝胶通常表现出低强度和低韧性。在本研究中，已发现水溶液中的可聚合两性离子单体在单体浓度≥50 wt%的高浓度下会表现出独特的液-液相分离现象，从而得到具有高抗压强度（6.5 MPa）和高韧性（2.12 kJ/m）的纯两性离子水凝胶和商用两性离子水凝胶。这种相分离及相应的聚集体可能是由在缺乏自由水条件下残留两性离子单体之间强烈的偶极-偶极相互作用引起的。液-液相分离和聚合物缠结的协同效应增强了纯聚两性离子水凝胶的机械强度、韧性、自我恢复能力和抗冻性能。此外，高度伸长但坚韧的聚两性离子水凝胶的高断裂能有助于提高抗裂纹扩展能力，这为其在组织工程、柔软灵活器件及电子应用中发挥更大作用并提高耐用性提供了支持。通过应变传感器和摩擦纳米发电机器件的开发与测试，展示了所提出的聚两性离子水凝胶的广泛应用。我们的研究结果为纯聚两性离子水凝胶的网络结构提供了新的见解。
