Preparation of Thermally Stimulated Patterned Hydrogel and Angle-Dependent Manipulation in Encrypted Pattern Display

Information storage materials with color-changing capabilities have garnered widespread attention for their ability to efficiently record complex information. In recent years, oriented hydrogels have made significant progress in the fields of information storage and encryption because of their rich and unique interference colors. However, introducing anisotropic microstructures in oriented hydrogels to rapidly create interference patterns remains a challenge. Additionally, interference-color-based encryption strategies remain limited and require further improvement. In this paper, a thermally responsive poly(vinyl alcohol) (PVA) hydrogel was fabricated through a stretch-induced combined with ion-assisted hydrogen bonding reconstruction strategy. A pen-tip soldering iron used as a contact thermal stimulus can rapidly dissociate the localized PVA crystalline domains, enabling the real-time creation of interference patterns. Moreover, innovative encryption strategies were proposed based on the angle-dependent properties of interference colors. By combining the hydrogels with different orientations and rotating them at different angles, the display of different pattern information was successfully realized. This approach avoids the complex steps of traditional interference-pattern preparation and offers a new paradigm for employing hydrogels in information encryption.