A kaleidoscopic hydrogel canvas for information encoding, encryption, and decryption via chemical-induced phase separation

Constructing an information storage or communication system, where countless pieces of information can be hidden like a canvas and revealed on demand through specific stimuli or decoding rules, is significant. In the present study, we developed a hydrogel canvas that leverages non-covalent interactions to induce phase separation in the polymer matrix, creating various “paintings”, including custom messages, using different chemical inks. Our strategy focuses on designing small molecule inks, with varying affinities with the hydrogel and specific responsiveness to stimuli, to achieve multiple changes such as color shifts, fluorescence emission, and dynamic optical image evolution. This skips the typical design approaches, such as incorporating responsive fluorophores into polymers for color emission through grafting or copolymerization, and thus avoids the complex processes involved in modifying and synthesizing functional polymers, along with the uncertainties in material properties that these processes bring.