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.
S. Malakooti and A. B. Ud Doulah and Y. Ren and V. N. Kulkarni and R. U. Soni and V. A. Edlabadkar and R. Zhang and S. L. Vivod and C. Sotiriou-Leventis and N. Leventis and H. Lu, "Meta-Aerogels: Auxetic Shape-Memory Polyurethane Aerogels," ACS Applied Polymer Materials, American Chemical Society (ACS), Oct 2021.
The definitive version is available at https://doi.org/10.1021/acsapm.1c00987
Keywords and Phrases
Aerogel; Auxetic; Metamaterial; Negative Poisson's Ratio; Polymer; Shape Memory
International Standard Serial Number (ISSN)
Article - Journal
© 2021 American Chemical Society (ACS), All rights reserved.
06 Oct 2021