Transparent
electromagnetic interference (EMI) shielding materials
can be used for specific optoelectronic applications. Herein, a uniform
silver nanowire (AgNW) network was fabricated on a commercial polyimide
film via a spraying method. The interconnected and effective conductive
network with welded junctions was fastened onto a sodium alginate-based
biopolymer substrate via rod-coating and -transferring methods to
improve electrical conductivity and optical transmittance of composite
films simultaneously. Moreover, another SA-based layer was coated
to encapsulate the AgNW network firmly, followed by cross-linking
with calcium ions (Ca2+), enabling the CA-based barrier
to protect the nanowires from corrosion by moisture and oxygen in
the air. Consequently, the obtained flexible CA/AgNWs/CA composite
film achieved a satisfactory EMI shielding effectiveness of 27.9 dB
with a favorable optical transmittance of 72.8% at 550 nm. Furthermore,
the composite film also showed excellent Joule heating performance
with a sensitive thermal response and good stability. The CA/AgNWs/CA
composite film retained a stable EMI shielding efficiency after being
exposed to air for 20 days with a slight decline in EMI SE upon cyclic
bending deformation and thermal shock treatment several times because
of the compact sandwich-like structure and cross-linked CA-based barrier.
Thus, the flexible and transparent CA/AgNWs/CA composite film holds
great promise for practical applications in optical electronic devices.