<p>Azobenzene polymers (azopolymers) have emerged as promising photosensitive building blocks for dynamically controllable surface patterning. Exploiting their multiple photoresponses, in combination with post-wrinkling light modulation, remains challenging for fabricating reconfigurable hierarchical micro/nanotextures. In this study, we propose a simple combined exposure strategy (i.e., pre-exposure followed by selective exposure) to modulate the as-wrinkled azopolymer surfaces, resulting in diverse, unprecedented hierarchical wrinkling microstructures. It is found that pre-exposure can lock the original wrinkle orientation and prevent wrinkle reorientation in unexposed regions during subsequent selective exposure. Consequently, a smart combination of pre-exposure duration and selective exposure size factor enables the creation of wrinkling wavelength-customized patterns with singly oriented, dually oriented, disordered, or ordered/disordered hybrid microstructures. Systematic experiments and theoretical analysis demonstrate that the reconfigurable wrinkling behavior is governed by the synergy and antagonism among photo-induced stress release, the photosoftening effect, and the boundary effect in azopolymer films. As demonstrated, the combined exposure strategy, applicable to other optically responsive as-wrinkled systems, such as poly(methyl methacrylate) and poly(lactic acid), facilitates reconfigurable hierarchical wrinkling micropatterns for advanced applications in information display/storage, anticounterfeiting, and optical gratings.</p>

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Spatiotemporal light modulation of as-wrinkled azopolymer film enabling reconfigurable hierarchical micropatterns for advanced photonics

  • Xi Wang,
  • Juanjuan Wang,
  • Zilong Wu,
  • Xue Han,
  • Xiaopeng Li,
  • Bin Wang,
  • Fuqi Wu,
  • Conghua Lu

摘要

Azobenzene polymers (azopolymers) have emerged as promising photosensitive building blocks for dynamically controllable surface patterning. Exploiting their multiple photoresponses, in combination with post-wrinkling light modulation, remains challenging for fabricating reconfigurable hierarchical micro/nanotextures. In this study, we propose a simple combined exposure strategy (i.e., pre-exposure followed by selective exposure) to modulate the as-wrinkled azopolymer surfaces, resulting in diverse, unprecedented hierarchical wrinkling microstructures. It is found that pre-exposure can lock the original wrinkle orientation and prevent wrinkle reorientation in unexposed regions during subsequent selective exposure. Consequently, a smart combination of pre-exposure duration and selective exposure size factor enables the creation of wrinkling wavelength-customized patterns with singly oriented, dually oriented, disordered, or ordered/disordered hybrid microstructures. Systematic experiments and theoretical analysis demonstrate that the reconfigurable wrinkling behavior is governed by the synergy and antagonism among photo-induced stress release, the photosoftening effect, and the boundary effect in azopolymer films. As demonstrated, the combined exposure strategy, applicable to other optically responsive as-wrinkled systems, such as poly(methyl methacrylate) and poly(lactic acid), facilitates reconfigurable hierarchical wrinkling micropatterns for advanced applications in information display/storage, anticounterfeiting, and optical gratings.