Integrating Photorewritable Fluorescent Information in Shape‐Memory Organohydrogel Toward Dual Encryption

Abstract

information, the ability to encrypt information has more important significance in information security. Nowadays, many scientists focus on the development of latemodel anti-counterfeiting materials, and corresponding strategies, [1][2][3][4] including bar code, two-dimensional code, holograms, luminous materials, and so on. Among them, luminous materials can be one of the best candidates for anti-counterfeiting due to their responsiveness to UV light, [5,6] the diversity of vivid colors [7,8] as well as various luminescence modes. [9,10] Given the excellent modifiability, containment and unique stimulus-responsiveness of polymeric hydrogels, [11][12][13][14] the combination of luminescence materials and intelligent hydrogels can make the stored information dynamic and improve security level. Up to now, a large number of studies have focused on information storage or information encryption [15][16][17][18] on the basis of fluorescent hydrogels. For example, Ji's group [19] fabricated a self-assemble hydrogel with polyvinyl alcohol (PVA) hydrogel doping three kinds of aggregation induced emission (AIE) fluorescent monomers. The prepared multi fluorescent hydrogel could store a large amount of information by introducing 1D barcodes or 2D codes and arraying the fluorescent blocks. Saunders and coworkers [20] employed microgels (MG) as As one of the severe global problems, counterfeiting information has brought a huge negative impact on every aspect of human society. Though various anticounterfeiting strategies, including fluorescent materials, are widely developed for dealing with the above problem, the information security level needs to be further improved due to sophisticated hacking techniques. In this study, an organohydrogel is designed by constructing interpenetrating organohydrogel networks, in which naphthalimide moieties (DEAN, greenyellow emission) are introduced in hydrophilic poly(N,N-dimethylacrylamide) (PDMA) hydrogel network and anthracene units (blue emission) are copolymerized in hydrophobic polystearate methacrylate (PSMA) organogel network. Triggered by UV light of 365 nm, the unimer-dimer transition occurs and leads the fluorescent color of organohydrogel to change from blue to faint yellow, making secret information be stored with the assistance of photomasks. Furthermore, by combining crystallization-induced shape memory performance, dual encryption can be achieved. This fluorescent organohydrogel provides a new idea for fabricating smart materials with the ability of encryption-decryption, which is of great significance in information security protection.

Dual Encryption in a Shape Memory Hydrogel with Rewritable Fluorescent Information

“…Actually, Chen and co‐workers newly reported an organohydrogel fabricated by interpenetrating hydrogel and organogel polymer networks, which could achieve dual encryption and self‐erasure by combining crystallization‐induced shape memory performance and recordable fluorescent patterns. [ 31 ] Owing to the cyclic light‐induced erasing/writing process, encrypted message can be erased and the smart gel‐based dual encryption platform can be reused for new information coding. This pioneering work demonstrated feasibility to develop stimuli‐responsive fluorescent hydrogels as dual encryption platforms with self‐erasure function, which effectively raise higher security levels and application value.…”

Ultra-stretchable, Antifatigue, Adhesive, and Self-Healing Hydrogels Based on the Amino Acid Derivative and Ionic Liquid for Flexible Strain Sensors

“…A hydrogel is a water-rich, soft material composed of a three-dimensional crosslinked polymer network structure with flexibility and extensibility. − Due to its similarity to biological tissues and other performance properties (such as electrical conductivity, self-adhesion, biocompatibility, and antibacterial properties), hydrogels have great potential in flexible wearable materials, smart sensors, tissue adhesives, and biomedical materials. − Among them, self-adhesion is a very important property since the hydrogel could directly attach to the skin or wound without additional treatment. − Inspired by biomolecules, adhesive hydrogels have been vigorously developed in recent years. For example, the mussel-inspired hydrogels containing catechol groups (such as dopamine and tannins) have received more and more attention. − Various types of interactions in such hydrogels, including π–π stacking, cation−π interactions, hydrophobic interactions, hydrogen bonding, and Michael addition, play a key role in adhesion strength .…”

A Time‐Dependent Fluorescent Hydrogel for “Time‐Lock” Information Encryption

“…Smart hydrogels, [22][23][24][25][26] specifically, timedependent color-tuneable hydrogels, are promising candidates for developing such materials on account of their dynamic optical properties on a time scale. [27][28][29] For example, Wang's group fabricated a kind of self-erasing rewritable paper based on the TiO 2 nanoparticle/methylene blue system and utilized it for transient information encryption. [30] In addition, fluorescent hydrogels with controllable emission (wavelength or intensity) are also candidates for the development of self-erasing materials due to their UV light-responsive features.…”