Back Cover: Brush‐Like Polymeric Gels Enabled Photonic Crystals toward Ultrasensitive Cosolvent Chromism

A man with a fishing rod to accurately pinpoint the target water molecule hidden among many ethanol molecules is illustrated in the cover picture. The fishing rod is shaped like the brush-like polymer structure used in the Research Article by Xiaoxia Le, Tao Chen et al. (e202414136). The rod body is composed of the acrylate backbones and the fishing line consists of the polyethylene glycol sidechains. The mountains in the background reflect the photonic crystal structure with different response degrees and corresponding structural colors.