# Mechanical/Thermomechanical–Electromagnetic Multifunctional Cellulose Nanofibril-MXene Aerogel-Based Metamaterials

## TL;DR

A new lightweight material made from cellulose and MXene shows multiple functions like superelasticity, fire resistance, and high electromagnetic shielding.

## Contribution

A novel CFO-CNFene metamaterial is developed with tunable magnetic particles and multifunctional properties for advanced applications.

## Key findings

- The CFO-CNFene metamaterial exhibits temperature-invariant superelasticity and ultralow thermal conductivity.
- The material achieves 99.999% electromagnetic interference shielding and 99.99% electromagnetic wave absorption.
- It supports applications in radar stealth and radiation protection due to its multifunctional properties.

## Abstract

As the latest breakthrough in the field of metamaterials, the interfacial coupling of topological and multistable states of wooden metamaterials remarkably enhances functionality and enables transformative applications. However, the high coupling and complex geometrical properties of the microlattice may impose constrain on design flexibility and scalability. Herein, we present a mechanically/thermomechanically electromagnetically multifunctional CFO-CNFene metamaterial featuring stochastically tunable aggregation-prone magnetic particles by in situ deposition of homogeneous magnetic CoFe2O4 nanoparticles through intermolecular interactions in a lightweight CNFene aerogel backbone. The resulting lightweight porous CFO-CNFene metamaterials exhibit remarkable characteristics, including temperature-invariant superelasticity and ultralow thermal conductivity (26.12 mW m−1 K−1), and, combined with the synergistic enhancement provided by the agglomerate-free double cross-linked ferromagnetic cobalt ferrite nanoparticles, result in comprehensive multifunctionalities, including rapid deformation, fire resistance, infrared thermal camouflage behavior, electromagnetic interference shielding efficiency (99.999%), and electromagnetic wave absorption efficiency (99.99%). This breakthrough supports the development of advanced electromagnetic stealth technologies for military and civilian applications, including radar stealth and radiation protection.