Lixian Guo,Hongyang Deng,Yuan Chen,Siyuan Zhang,Chunrong Tian,Xiaolian Qiang,Shuen Liang,Jianhua Wang,Ningning Song
Recently, PI aerogels have demonstrated immense potential for applications across various fields due to their outstanding properties, however, the trade-off between strength and toughness has hindered broader use. To overcome this challenge, we have achieved a synergistic enhancement of pore structure and framework by adjusting molecular chain rigidity and cation-π crosslinking density, leading to significant improvement in strength and toughness of PI aerogels. The results reveal that the cation-π bonds help the pore structure transition from a lamellar stacking arrangement to a web-like pore structure, accompanied by a significant reduction in pore size. Peculiarly, as the flexibility of molecular chains increases, the web-like pore structure shifts from disordered cylindrical arrays to regular hexagonal prism arrangement. Moreover, the varied chain rigidity also endows the cation-π bonds with different binding energy. Hence, PI aerogel based on BTDA exhibits the highest mechanical enhancement due to the synergistic effects of more ordered pore structure and much strong cation-π interactions, with its specific strength, specific modulus, and toughness increasing by 154.5%, 251.8%, and 164.3%, respectively. Additionally, it also demonstrates an ultralow density (0.0489 g/cm 3 ) and outstanding thermal insulation performance (0.0427 W/m·K). This presents a novel strategy for fabricating low-density, high-strength-toughness, and low thermal conductivity PI aerogels, which is beneficial for further applications of PI aerogels.
Deshuai Kong,Yunmeng Li,Biao Yang,Yaokun Pang,Hua Yuan,Cong Du,Yeqiang Tan
Extrusion-based 3D printing is a facile technology to construct complex structures of hydrogels, especially for tough hydrogels that have shown demonstrated potential in load-bearing materials and tissue engineering. However, 3D-printed hydrogels often possess mechanical properties that do not guarantee their usage in tissue-mimicking, load-bearing components, and motion sensors. This study proposes a novel strategy to construct high-strength and anisotropic Fe 3+ cross-linked poly(acrylamide- co -acrylic acid)/sodium alginate double network hydrogels. The semi-flexible sodium alginate chains act as a “conformation regulator” to promote the formation of strong intermolecular interactions between polymer chains and lock the more extended conformation exerted by the pre-stretch, enabling the construction of 3D-printed hydrogel structures with high orientation. The equilibrated anisotropic hydrogel filaments with a water content of 50–60 wt.% exhibit outstanding mechanical properties (tensile strength: 9–44 MPa; elongation at break: 120–668%; Young's modulus: 7–62 MPa; toughness: 26–52 MJ m − 3 ). 3D-printed anisotropic hydrogel structures with high mechanical performance show demonstrated potential as loading-bearing structures and electrodes of flexible triboelectric nanogenerators for versatile human motion sensing.
危险品化学品经营许可证（带存储）