Thermochromic Hydrogels with Opaque‐Transparent Gradient Transition for Switchable Window and Temperature Monitor

In recent years, the thermochromic hydrogel was acted as suitable sandwiching material to adjust light transmission. However, to accurately control the thermochromic temperature in a wide range still was a significant challenge. Here, a simple method was explored to prepare hydrogels with gradient opaque‐transparent transition thermochromic temperature from 5 °C to 53 °C, which was regulated by the aggregation state of sodium dodecyl sulfate micelles by adding potassium tartrate hemihydrate and positive ions. The positive ions, including Li+, Na+, and K+, and the accuracy was controlled at 1 °C. Moreover, the transmittance of the hydrogel was not changed when the thermochromic temperature was adjusted. As a result, an intelligent window was fabricated by utilizing thermochromic hydrogel as a sandwiching layer into the outer glass layers, which could effectively and stably regulate the visible and infrared light. The temperature monitors/detectors were also designed, which showed excellent temperature monitoring/detecting ability. Therefore, this low‐cost, high‐efficient, large‐scale prepared thermochromic hydrogel provided more potential for intelligent temperature devices.