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Download fileA Versatile Strategy for Transparent Stimuli-Responsive Interference Coloration
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posted on 2019-01-23, 00:00 authored by Seyedali Banisadr, Adebola Oyefusi, Jian ChenThe bioinspired stimuli-responsive
structural coloration offers
a wide variety of potential applications, ranging from sensing to
camouflage to intelligent textiles. Because of its design simplicity,
which does not require multilayers of materials with alternative refractive
indices or micro- and nanostructures, thin film interference represents
a promising solution toward scalable and affordable manufacturing
of high-quality responsive structural coloration systems. However,
thin films of polymers with appropriate thickness generally do not
exhibit visible structural colors if they are directly deposited on
transparent substrates such as glass. In this work, a versatile new
strategy that enables transparent stimuli-responsive interference
coloration (RIC) in the polymer–metal–substrate system
is presented. The key concept is to use an ultrathin metal layer as
an optical filter instead of high refractive index substrate or highly
reflective substrate. Such an optical filter layer allows tuning of
the degree of transparency, the constructive interference reflection
light, and complementary destructive interference transmission light
via changing the metal layer thickness. Real-time, continuous, colorimetric
RIC sensors for humidity, organic vapor, and temperature are demonstrated
by using different stimuli-responsive polymers. The transparent RIC
film on glass shows strong coupling of constructive interference reflected
colors and complementary destructive interference transmitted colors
on opposite sides of the film. Such transparent RIC film allows for
the proof-of-concept demonstration of a self-reporting, humidity-sensing
window.