Super-elasticity at 4 K of covalently crosslinked polyimide aerogels with negative Poisson’s ratio
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The deep cryogenic temperatures encountered in aerospace present significant challenges for the performance of elastic materials in spacecraft and related apparatus. Reported elastic carbon or ceramic aerogels overcome the low-temperature brittleness in conventional elastic polymers. However, complicated fabrication process and high costs greatly limited their applications. In this work, super-elasticity at a deep cryogenic temperature of covalently crosslinked polyimide (PI) aerogels is achieved based on scalable and low-cost directional dimethyl sulfoxide crystals assisted freeze gelation and freeze-drying strategy. The covalently crosslinked chemical structure, cellular architecture, negative Poisson’s ratio (−0.2), low volume shrinkage (3.1%), and ultralow density (6.1 mg/cm3) endow the PI aerogels with an elastic compressive strain up to 99% even in liquid helium (4 K), almost zero loss of resilience after dramatic thermal shocks (∆T = 569 K), and fatigue resistance over 5000 times compressive cycles. This work provides a new pathway for constructing polymer-based materials with super-elasticity at deep cryogenic temperature, demonstrating much promise for extensive applications in ongoing and near-future aerospace exploration.
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Cheng, Yang, Zhang, Xiang, Qin, Yixiu, et al.. "Super-elasticity at 4 K of covalently crosslinked polyimide aerogels with negative Poisson’s ratio." Nature Communications, 12, (2021) Springer Nature: https://doi.org/10.1038/s41467-021-24388-y.