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Download fileMeta-Aerogels: Auxetic Shape-Memory Polyurethane Aerogels
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posted on 2021-10-06, 10:16 authored by Sadeq Malakooti, A. B. M. Shaheen ud Doulah, Yao Ren, Vijay N. Kulkarni, Rushi U. Soni, Vaibhav A. Edlabadkar, Runyu Zhang, Stephanie L. Vivod, Chariklia Sotiriou-Leventis, Nicholas Leventis, Hongbing LuShape-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.
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pir – purnegative poisson ’deployable space structuresbase polymer (<approximately − 0heating actuation stepauxetic effect manifestedglass transition temperatureg </ subheating back>< subauxetic shapestructural designstowed indefinitelysoft roboticsplanetary habitatsmemory responsemacro scaleindustries spanningcompressive strainbroad rangeaerospace sectors