Near infrared-sensitive smart windows from Au nanorod–polymer hybrid photonic hydrogels

Abstract

The thermotropic polymer hydrogel shows promising potential in smart windows due to its tunability from transparency to opaque under solar irradiation. However, the transformation process is relatively slow because of the low energy transformation efficiency of solar to heat. Herein, we demonstrated a poly(N-isopropyl acrylamide-co-acrylamide)-based smart window with gold nanorods. The introduced gold nanorods substantially increased the energy transformation efficiency of solar to heat due to its plasma resonance, enabling the transformation from transparency to opaque within ∼15 min. Besides, we endowed the smart window with the photonic structure to bring about the visually perceptible color change. The smart window comprising of a hybrid photonic hydrogel could switch its structural color and transparency (100% to 80%) within ∼6 s upon near infrared light irradiation. The smart window's transparency transform time could be modulated from 6 to 12 s for personal thermal management. Moreover, the hybrid photonic hydrogel shows excellent reversibility and good passive cooling ability. Overall, our near infrared-sensitive smart window with visually perceptible color change would open an avenue for fabricating smart materials and constructing an indoor thermal management system.