Wrinkled Structure and Morphology Transition of Poly(vinylidene Fluoride Cohexafluoropropylene) Films for Smart Windows

Wrinkling phenomena has attracted wide attention owing to its applications in anticounterfeiting patterns, smart windows, flexible devices, and sensors, and the dynamic morphological transformations of wrinkle structure extend the application in dynamic displays, patterning, and surface wetting. However, developing simple and effective wrinkle morphology transformation strategies to design smart windows with good repeatability and stable properties presents ongoing challenges. In this paper, morphology transition of the wrinkle structure is presented to develop potential applications in smart window and pattern fabrication. At first, a nanoscale wrinkled structure was fabricated by immersing an ionic liquid mixed solution with poly(vinylidene fluoride)-hexafluoropropylene over a colloidal assembly based on the mismatch modulus between the surface layer and the interior during solvent evaporation. The wrinkle structure can be erased to form a pattern by inkjet printing based on the ink-induced dispersion of the ionic liquid. Interestingly, the wrinkled and erased structures have completely opposite optical reversible responsiveness to humidity changes, which forms the basis of a smart window. This wrinkled structure shows promising applications in anticounterfeit patterning, smart windows, and antiglare materials, which provides guidelines for the development of wrinkled-based optic materials and devices.