Designing Rewritable Dual‐Mode Patterns using a Stretchable Photoresponsive Polymer via Orthogonal Photopatterning

The fabrication of dual‐mode patterns in the same region of a material is a promising approach for high‐density information storage, new anti‐counterfeiting technologies, and highly secure encryption. However, dual‐mode patterns are difficult to achieve because the two patterns in one material may interfere with each other during fabrication and usage. The development of noninterfering dual‐mode patterns requires new materials and patterning techniques. Herein, a novel orthogonal photopatterning technique is reported for the fabrication of noninterfering dual‐mode patterns on an azopolymer P1. P1 is a unique material that exhibits both photoinduced reversible solid‐to‐liquid transitions and good stretchability. In the first step of orthogonal photopatterning, patterned photonic structures are fabricated on a P1 film via masked nanoimprinting controlled by photoinduced reversible solid‐to‐liquid transitions. In the second step, the P1 film is stretched and irradiated with polarized light through a photomask, which generates a chromatic polarization pattern. In particular, the photonic structures and chromatic polarization in the dual‐mode pattern are noninterfering. Another feature of dual‐mode patterns is that they are rewritable via photo‐, thermal, or solution reprocessing, which are useful for recycling and reprogramming. This study opens an avenue for the development of novel materials and techniques for photopatterning. Two patterns are observed in one film! Orthogonal photopatterning is developed to fabricate dual‐mode patterns in stretchable azopolymers that exhibit photoinduced reversible solid‐to‐liquid transitions. The dual‐mode pattern contains photonic and chromatic polarization patterns, which do not interfere with each other. The dual‐mode patterns are rewritable and reprocessable. They are promising materials for anti‐counterfeiting, information storage, and encryption applications.