2022 Volume 10 Issue 3 Pages 140-144
We investigate the transmittance properties of a thermo-responsive smart window utilizing poly(N-isopropyl acrylamide) aqueous solution (PNIPAM) that exhibits a lower critical solution temperature (LCST)-type phase separation. The transmittance in the transparent state remained around 80 %, which is almost the same when the device is empty. In contrast, the transmittance in the opaque state for the device with Mn ∼40 K and Mn ∼10 K decreased 55 % to 10 % with increasing PNIPAM concentration. Moreover, with increasing PNIPAM concentration, the clouding point for the device decreased slightly because of emphasizing the cooperativity in hydration, even when the device thickness was as thin as 20 μm. Although the transmittance for the device in the opaque state is controllable using the PNIPAM concentration. There is however a trade-off between transmittance and its variation in the opaque state. We believe these results to be useful in developing thermo-responsive smart window products.
