Tattooing Plastics with Reversible and Irreversible Encryption

Self‐healing materials are explored for restoring mechanical, electrical, and chemical properties. Inspired by the process of tattooing on human skin, a method for engraving non‐permanent or permanent messages on plastics is developed. A self‐healing polymer containing dynamic disulfide bonds is employed as substrate for encryption of written messages. The polymer is engraved with a dye solution which is subsequently covered by the polymer matrix upon activation with temperature increase. The dye is then located at the subsurface of the substrate so that the information cannot be removed easily by wear or extraction with solvents. Therefore, self‐healing polymers can be applied as sustainable substrates for reversibly and irreversibly engraving information.