Title

Meta-Aerogels: Auxetic Shape-Memory Polyurethane Aerogels

Abstract

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.

Department(s)

Chemistry

Comments

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

International Standard Serial Number (ISSN)

2637-6105

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2021 American Chemical Society (ACS), All rights reserved.

Publication Date

06 Oct 2021

Share

 
COinS