Revealing
Surface/Interface Chemistry of the Ordered
Aramid Nanofiber/MXene Structure for Infrared Thermal Camouflage and
Electromagnetic Interference Shielding
The
past decade has witnessed the advances of infrared (IR) thermal
camouflage materials, but challenges remain in breaking the trade-off
nature between emissivity and mechanical properties. In response,
we identify the key role of a moderate reprotonation rate in the aramid
nanofiber (ANF)/MXene film toward a surface-to-bulk alignment. Theoretical
simulation demonstrates that the ordered ANF/MXene surface eliminates
the local high electric field by field confinement and localization,
responsible for the low IR emissivity. By scrutinizing the surface/interface
chemistry, the processing optimization is achieved to develop an ordered
and densely stacked ANF/MXene film, which features a low emissivity
of 16%, accounting for sound IR thermal camouflage performances including
a wide camouflage temperature range of 50–200 °C, a large
reduction in radiation temperature from 200.5 to 63.6 °C, and
long-term stability. This design also enables good mechanical performance
such as a tensile strength of 190.8 MPa, a toughness of 12.1 MJ m–3, and a modulus of 7.9 GPa, responsible for better
thermal camouflage applications. The tailor-made ANF/MXene film further
attains an electromagnetic interference (EMI) shielding effectiveness
(40.4 dB) in the X-band, manifesting its promise for IR stealth compatible
EMI shielding applications. This work will shed light on the dynamic
topology reconstruction of camouflage materials for boosting thermal
management technology.