Highly Flexible, Multipixelated Thermosensitive Smart Windows Made of Tough Hydrogels

• DOI: 10.1021/acsami.7b08907
• Publication Date: 2017-08-24T15:12:25Z
• Authors: Thanh-Giang La; Xinda Li; Amit Kumar; Yiyang Fu; Shu Yang; Hyun-Joong Chung
• Keywords: Opacity; Infrared heater; Black-body radiation; Contrast ratio

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