Chemically Gated Hydrogen Bonds Unlock Multifunctional Humidity Responses in 3D Topological Blue Phase Liquid Crystal Polymers

Abstract Harnessing reconfigurable hydrogen bonds (H‐bonds) offers a powerful strategy to program latent functionalities in smart polymers. Here, a blue phase liquid crystal (BPLC) polymer featuring a dense H‐bond network derived from carboxylic acid monomers is designed. This network acts as a chemically‐gated system: a simple, reversible acid‐base treatment switches the material between a passive “locked” state, dominated by H‐bonds, and a highly active “unlocked” state, driven by ionic crosslinking. This activation unlocks a suite of exceptional humidity‐responsive functions, including a rapid, ultra‐wide spectral band chromatic shift (from 445 to 603 nm) and powerful mechanical actuation (bending angle >225°). The unique 3D topological network of the BPLC is revealed to be critical for this high‐performance output, providing interconnected nanochannels for efficient mass transport. The platform's versatility is demonstrated in applications ranging from multi‐level anti‐counterfeiting and biomimetic actuators to wearable respiratory sensors. This research establishes a potent design paradigm for developing integrated, high‐performance smart materials with programmable, on‐demand functionality.