Polymerization-Pathway-Dependent Zwitterionic Hydrogels for Time-Gated Information Encryption and Irreversible Optical Erasure

Chameleon-like adaptive coloration inspires dynamic information camouflage, yet translating temporally programmable optical behavior into synthetic soft materials remains challenging. Here, we develop a zwitterionic pVS hydrogel for time-gated information encryption, decryption, and irreversible optical erasure. The system uses the established alkali-responsive fluorescence of VPES-derived units as the optical basis, while the SBMA-rich zwitterionic network suppresses swelling and preserves pattern fidelity. Spatially separated UV- and thermally initiated polymerization pathways generate domains with distinct initial emission states and alkaline-response trajectories within the hydrogel, allowing polymerization history to function as an intrinsic optical key. Quantitative kinetic analysis reveals progressive fluorescence convergence between the UV- and thermally initiated domains, with the red-emission contrast decreasing from 0.667 to 0.012 during prolonged alkaline treatment and preventing subsequent recovery of QR-code readability after acid treatment. This convergence establishes an operational time window for information security: short alkaline exposure produces a recoverable encrypted state, whereas excessive exposure permanently eliminates the optical contrast required for QR-code recognition, resulting in irreversible information self-destruction. This work provides a kinetically controlled hydrogel strategy for transient information protection and time-limited optical authentication.