Regulable Mixed‐Solvent‐Induced Phase Separation in Hydrogels for Information Encryption. Issue 52 (4th November 2022)

• Record Type: Journal Article
• Authors: Li, Min; Lu, Honglang; Wang, Xiaoyu; Wang, Zhisen; Pi, Menghan; Cui, Wei; Ran, Rong
• Is Part Of: Small. Volume 18:Issue 52(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-04
• Subjects: diffusion coefficient -- hydrogel -- information encryption -- phase separation -- swelling behavior; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202205359
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: The rapid progress of information technology is accompanied by plenty of information embezzlement and forgery, but developing advanced encryption technologies to ensure information security remains challenging. Phase separation commonly leads to a dramatic change in the transmittance of hydrophilic polymer networks, which is a potential method for information security but is often neglected. Here, taking the polyacrylamide (PAAm) hydrogel system as a typical example, facilely adjustable information encryption and decryption via its regulable phase separation process in ethanol/water mixed solvent, are reported. By controlling the osmotic pressure of the external and internal environment, it is demonstrated that the diffusion coefficient during deswelling and reswelling, as well as the corresponding change of transmittance of the gel, can be well controlled. Relatively high osmotic pressure leads to rapid phase separation of the initial gel but slow phase remixing of the phase‐separated gel, opening the opportunity of applying the gel as a reversible information encryption device. As proof‐of‐concept demonstrations, several stable and reversible information encryption and decryption systems by making use of the phase separation process of the gels are designed, which are expected to inspire the development of next‐generation soft devices for information technology. Abstract : The homogeneous phase of polyacrylamide hydrogels progressively separates into polymer‐rich and polymer‐dilute phases with contrasting network chain densities in good/poor mixed solvents, leading to a transparent–opaque transition. Such a phase separation behavior is reversible and can be well regulated by the internal and external solvent strength of the gel, promising its application in adjustable information encryption.