2 research outputs found
Highly Flexible, Multipixelated Thermosensitive Smart Windows Made of Tough Hydrogels
In
a cold night, a clear window that will become opaque while retaining
the indoor heat is highly desirable for both privacy and energy efficiency.
A thermally responsive material that controls both the transmittance
of solar radiance (predominantly in the visible and near-infrared
wavelengths) and blackbody radiation (mainly in the mid-infrared)
can realize such windows with minimal energy consumption. Here, we
report a smart coating made from polyampholyte hydrogel (PAH) that
transforms from a transparency state to opacity to visible radiation
and strengthens opacity to mid-infrared when lowering the temperature
as a result of phase separation between the water-rich and polymer-rich
phases. To match a typical temperature fluctuation during the day,
we fine-tune the phase transition temperature between 25 and 55 °C
by introducing a small amount of relatively hydrophobic monomers (0.1
to 0.5 wt % to PAH). To further demonstrate an actively controlled,
highly flexible, and high-contrast smart window, we build in an array
of electric heaters made of printed elastomeric composite. The multipixelated
window offers rapid switching, ∼70 s per cycle, whereas the
device can withstand high strain (up to 80%) during operations
Highly Flexible, Multipixelated Thermosensitive Smart Windows Made of Tough Hydrogels
In
a cold night, a clear window that will become opaque while retaining
the indoor heat is highly desirable for both privacy and energy efficiency.
A thermally responsive material that controls both the transmittance
of solar radiance (predominantly in the visible and near-infrared
wavelengths) and blackbody radiation (mainly in the mid-infrared)
can realize such windows with minimal energy consumption. Here, we
report a smart coating made from polyampholyte hydrogel (PAH) that
transforms from a transparency state to opacity to visible radiation
and strengthens opacity to mid-infrared when lowering the temperature
as a result of phase separation between the water-rich and polymer-rich
phases. To match a typical temperature fluctuation during the day,
we fine-tune the phase transition temperature between 25 and 55 °C
by introducing a small amount of relatively hydrophobic monomers (0.1
to 0.5 wt % to PAH). To further demonstrate an actively controlled,
highly flexible, and high-contrast smart window, we build in an array
of electric heaters made of printed elastomeric composite. The multipixelated
window offers rapid switching, ∼70 s per cycle, whereas the
device can withstand high strain (up to 80%) during operations