Meta-Aerogels: Auxetic Shape-Memory Polyurethane Aerogels


Shape-memory poly(isocyanurate-urethane) (PIR-PUR) aerogels are low-density monolithic nanoporous solids that remember and return to their permanent shape through a heating actuation step. Herein, through structural design at the macro scale, the shape-memory response is augmented with an auxetic effect manifested by a negative Poisson's ratio of approximately -0.8 at 15% compressive strain. Thus, auxetic shape-memory PIR-PUR monoliths experience volume contraction upon compression at a temperature above the glass transition temperature of the base polymer (Tg ≈ 30 °C), and they can be stowed indefinitely in that temporary shape by cooling below Tg. By heating back above Tg, the compressed/shrunk form expands back to their original shape/size. This technology is relevant to a broad range of industries spanning the commercial, aeronautical, and aerospace sectors. The materials are referred to as meta-aerogels, and their potential applications include minimally invasive medical devices, soft robotics, and situations where volume is at a premium, as for example for storage of deployable space structures and planetary habitats during transport to the point of service.




For financial support, the authors thank the NSF under Award Numbers CMMI-1661246, CMMI-1636306, CMMI-1726435, CMMI-1727960, CMMI-1530603 (subcontract to MS&T from Tufts University), DoE DE-NA0003962, and Sandia National Laboratories grant (2202023).

Keywords and Phrases

Aerogel; Auxetic; Metamaterial; Negative Poisson's Ratio; Polymer; Shape Memory

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Article - Journal

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Publication Date

06 Oct 2021