Photo‐Directed Growth of Surface Micro‐Patterns on Photosensitive Semicrystalline Polymers

Abstract Patterning polymeric materials with controllable microstructures can meet diversified requirements and realize promising applications. Exploring micro‐/nano‐pattern methodology offers possibilities for future techniques, however, the self‐organized growth of polymeric materials has some limitations and the development of direct and noncontact patterning processes is still challenging. In this work, the study presents a facile strategy for endowing polymers with spatially regulated microstructures by direct photo‐printing, which incorporates both advantages of typical top‐down and bottom‐up approaches. By employing the photodimerization of anthracene‐containing semi‐crystallized polymers, the gradient crosslinking results in a mismatch of thermal expansion coefficients between the crosslinked surface and the uncrosslinked bottom layer. After heating treatment, constrained by the crosslinked surface, the uncrosslinked bottom polymer of the molten state in the exposed region tends to flow and migrate toward the unexposed region, similar to a volcanic eruption, which accurately determines the height and morphology of pattern. Besides, the well‐defined patterns can controllably grow upon thermal treatment due to phase transformation and migration. The versatility of the proposed strategy not only provides a brand‐new reliable platform to pattern functional materials with photo‐regulated and reversible microstructures, but also promotes the development of smart materials that can find applications in information safety, reversible microfluidics, and electronic devices.