Tough and Multifunctional Composite Film Actuators Based on Cellulose Nanofibers toward Smart Wearables

Although
humidity-responsive actuators serve as a promising candidate
in smart wearables, artificial muscles, and biomimetic devices, most
of them derived from synthetic polymers could not simultaneously achieve
multifunctional properties. In this work, a cellulose nanofiber (CNF)-based
film actuator with high mechanical properties, excellent Joule heating,
and antibacterial capability is successfully constructed by integrating
with Ti3C2Tx (MXene)
and tannic acid (TA) via a vacuum-assisted filtration approach. Owing
to the unique nacrelike structure and strong hydrogen bonds, the tensile
strength and toughness of the composite film could reach 275.4 MPa
and 10.2 MJ·m–3, respectively. Importantly,
the hydrophilic nature of CNFs and alterable interlayer spacing of
MXene nanosheets endow the composite film with sensitive humidity
response and extraordinary stability (1000 cycles). With the assistance
of MXene nanosheets and TA, the composite film could not only present
outstanding Joule heating but also possess remarkable antibacterial
properties against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Benefiting from the above merits, the proof-of-concept smart garment
is assembled by the as-prepared film and is capable of regulating
humidity and temperature.