3D‐Printing Thermo‐Responsive Photonic Inks Based on Cellulose Semi‐Interpenetrating Liquid Crystal Networks

Abstract 3D‐printable photonic crystals are widely utilized in sensors, painting decoration, and information encryption. The development of photonic inks capable of forming complex shapes and exhibiting flexible color changes enables the fabrication of structural‐color devices with unique structures and specialized functions, while achieving collaborative control over 3D printability and dynamic color‐changing function remains a significant challenge. Here, printable and thermosensitive photonic inks are demonstrated through the co‐assembly of hydroxypropyl cellulose (HPC) and hydroxyethyl acrylate into cholesteric liquid crystals. The semi‐interpenetrating network created by HEA polymerization, along with the hydrogen bonding between the co‐phases, facilitates the 3D printing of complex objects. Moreover, this network maintains the cholesteric phase structure while reducing the phase separation of HPC, enabling the manipulation of varying degrees of color change, with sensitivities ranging from 6.4 to 3.0 nm °C⁻¹. Through 3D printing, these photonic inks can be utilized to create both 2D and 3D objects with dynamic thermochromic properties. This work offers a simple and instructive strategy for developing flexible and responsive photonic materials.