Orthogonal Photo-chemistry Towards Direct Encryption of a 3D Printed Hydrogel.

Encryption technologies are essential for information security and product anti-counterfeiting, but they are typically restricted to planar surfaces. Encryption on complex 3D objects offers great potential to further improve security. However, it is rarely achieved owing to the lack of encoding strategies for non-planar surfaces. Here, we report an approach to directly encrypt on a 3D printed object employing orthogonal photo-chemistry. In this system, visible light photo-chemistry is used for 3D printing of a hydrogel and ultraviolet light is subsequently employed to activate its geometrically complex surface through the dissociation of ortho-nitrobenzyl ester units in a spatio-selective manner for information coding. Our approach offers a new way for more reliable encryption and the underlying orthogonal photo-chemistry can be extended towards functional modification of 3D printed products beyond information protection. This article is protected by copyright. All rights reserved.