With the continuous advancement of information technology, the requirements for the information storage capacity of materials are getting higher and higher. However, information code materials usually only store a single piece of information. In order to improve their storage capacity, aggregation‐induced emission (AIE) supramolecular adhesive hydrogels with different fluorescent colors are prepared, and a “Codes in Code” method is used to demonstrate the storage capacity for large amounts of information. Four kinds of poly(vinyl alcohol) (PVA) supramolecular hydrogels with different fluorescent colors are prepared; based on the hydrogen bonds on the hydrogel surface, these hydrogels can be assembled into a hydrogel, G5, which shows multiple fluorescent colors under the irradiation of UV light. When many 1D barcode patterns or/and 2D code patterns are incorporated into G5, not only a kind of 3D information but also plenty of 1D or/and 2D information can be stored. Therefore, the information codes prepared by the “Codes in Code” method can store a large amount of information.

Encryption is critical to information security; however, existing chemical-based information encryption strategies are still in their infancy. We report here a new approach to chemical encryption involving a supramolecular gel QR (quick response) code with multiple encryption functions. Three color “turn-on” supramolecular polymer gels, G1–G3, were prepared that produce pink, purple, and yellow colors when subject to treatment with acetic acid vapor, UV light, and methanolic FeCl3, respectively. As the result of hydrogen-bonding interactions at the gel interfaces, the three gels can be assembled to produce gel G4. Engraving a QR code pattern onto G4 then gave gel G5. When one or two stimuli are applied to the individual pieces corresponding to the QR engraved versions of the gels G1–G3 making up G5, a complete scannable pattern is not displayed, and the stored information cannot be recognized. Only when three different stimuli are applied at the same time does G5 give a complete recognizable pattern allowing the stored information to be retrieved. This strategy was applied to the decryption-based opening of a coded lock.

In this review, we summarize the chemistry of water compatible supramolecular polymers (WCSPs) based on the core supramolecular approaches at play, namely hydrogen-bonding arrays, electrostatic interactions, large π-conjugated subunits, host–guest interactions, and peptide-based systems, respectively. We discuss both synthesis and polymer structure, as well as the underlying design expectations and potential applications.

Issues of molecular weight determination have been central to the development of supramolecular polymer chemistry. Whereas relationships between concentration and optical features are established for well-behaved absorptive and emissive species, for most supramolecular polymeric systems no simple correlation exists between optical performance and number-average molecular weight (Mn). As such, the Mn of supramolecular polymers have to be inferred from various measurements. Herein, we report an anion-responsive supramolecular polymer [M1·Zn(OTf)2]n that exhibits monotonic changes in the fluorescence color as a function of Mn. Based on theoretical estimates, the calculated average degree of polymerization (DPcal) increases from 16.9 to 84.5 as the monomer concentration increases from 0.08 mM to 2.00 mM. Meanwhile, the fluorescent colors of M1 + Zn(OTf)2 solutions were found to pass from green to yellow and to orange, corresponding to a red shift in the maximum emission band (λmax). Therefore, a relationship between DPcal and λmax could be established. Additionally, the anion-responsive nature of the present system meant that the extent of supramolecular polymerization could be regulated by introducing anions, with the resulting change in Mn being readily monitored via changes in the fluorescent emission features.

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