Tough and rapidly stimuli-responsive luminescent hydrogels for multi-dimensional information encryption and storage

In modern society, information leakage is a very important issue during our dairy life. Multi-dimensional information encryption and storage are effective ways to increase the security level. Herein, a serials of rapidly stimuli-responsive, tough fluorescent hydrogels have been fabricated by doping Ln3+ ions (Ln = Eu, Tb, Eu/Tb) into poly(N-acryloyl glycinamide-co-potassium 6-acryl-amidopicolinate) (P(NAGA-co-K6APA)) hydrogel networks which are prepared by one-pot copolymerization. The dynamic lanthanide complexes could not only serve as photoluminescent emitters but also cross-linking points to provide additional strength to the hydrogel network. The tensile fracture stress and Young's modulus can reach up to 3.9 MPa and 0.66 MPa, respectively, comparable to previously reported tough hydrogels. Moreover, because of these dynamic lanthanide coordination bonds, the luminescent hydrogels showed very fast and reversible responsiveness via direct alternating exposure to acid and base without luminance fatigue for at least five cycles. Remarkably, time-dependent luminescence fading process of this dynamic lanthanide complexes provides these hydrogels to be applied in multi-dimensional information encryption and decryption.