Chen Jia, Chen Zhilin, Hou Xianbo, Chen Liming
College of Aerospace Engineering, Chongqing University, Chongqing 400030, China.
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400030, China.
ACS Appl Mater Interfaces. 2024 Oct 23;16(42):57746-57759. doi: 10.1021/acsami.4c13806. Epub 2024 Oct 11.
Efficient thermal insulators that can maintain their efficacy at extreme temperatures are in pressing demand, particularly in fields such as energy saving, aerospace, and sophisticated equipment. Herein, a novel and facile polymerization-regulated optimal strategy is adapted to realize the comprehensive performance of polyimide (PI) aerogel membranes with mechanical robustness, high flexibility, hydrophobicity, light transmittance, and efficient thermal insulation. Benefiting from the hydrolysis of monomers and chemical imidization reaction process verified by a thermo-chemo-mechanically coupled theoretical model, the viscosity of precursors, shrinkage rate, and microstructure of aerogels are precisely controlled, leading to a low thermal conductivity range of 0.023-0.044 W/(m·K). The fabricated PI aerogel membranes, which undergo a remarkable transformation from their initial brittle and opaque nature to a state of high flexibility and transparency, exhibit a 3.0 times increase in tensile strength (4.6 MPa) and a 8.4 times improvement in elongation at break (20.6%) over previous studies while demonstrating an exceptional light transmittance of 92.5% across a wide spectral range from 500 to 2500 nm. Additionally, the PI aerogel membranes possess superior mechanical properties and a wide temperature resistance range extending from -196 to 300 °C. These flexible PI aerogel membranes can be effectively adjusted to meet the practical application of a circular ring solar thermal collector, which displayed a high solar heat collection temperature of 135 °C at a thickness of 0.5 mm. The coordination between the thermophysical properties and mechanical properties of the PI aerogel membranes in this work holds great promise for application requirements of thermal insulators in optical elements under harsh environments.
迫切需要能够在极端温度下保持其功效的高效热绝缘体，特别是在节能、航空航天和精密设备等领域。在此，采用了一种新颖且简便的聚合调控优化策略，以实现具有机械强度、高柔韧性、疏水性、透光率和高效隔热性能的聚酰亚胺（PI）气凝胶膜的综合性能。受益于单体水解和化学亚胺化反应过程（由热化学机械耦合理论模型验证），前驱体的粘度、收缩率和气凝胶的微观结构得到精确控制，导致热导率范围低至0.023 - 0.044 W/(m·K)。制备的PI气凝胶膜从最初的脆性和不透明状态显著转变为高柔韧性和透明状态，与之前的研究相比，拉伸强度提高了3.0倍（4.6 MPa），断裂伸长率提高了8.4倍（20.6%），同时在500至2500 nm的宽光谱范围内具有92.5%的优异透光率。此外，PI气凝胶膜具有优异的机械性能和从 -196到300°C的宽耐温范围。这些柔性PI气凝胶膜可以有效地进行调整，以满足圆环太阳能集热器的实际应用，在厚度为0.5 mm时显示出135°C的高太阳能集热温度。这项工作中PI气凝胶膜的热物理性能和机械性能之间的协同作用对于恶劣环境下光学元件中热绝缘体的应用需求具有很大的前景。
