Unconventional Approaches to Light-Promoted Dynamic Surface Morphing on Polymer Films

Recent progress in research of light-promoted surface morphing on polymer materials is reviewed. Photoinduced mass transport motions in azobenzene polymers leading to surface relief gratings (widely called SRGs) formation are wellknown and extensively discussed. Among many efforts, this article focuses on unconventional approaches, most of which are seemingly less highlighted. The first part introduces investigations using azobenzene polymers; introducing supramolecular approaches with tunable and removable azobenzene units, self-structuring of surface morphology upon single laser beam irradiation, photo-triggered migration via Marangoni flow, SRG formation and other functions of polymer brushes etc. The second part overviews the mass transport motions driven by other photoreaction classes such as photopolymerization, photocrosslinking, and photoisomerization of non-azobenzene components. The final part describes new dynamic surface morphing processes observed in fingerprint texture of liquid crystals and liquid crystal polymer networks, which can be applied to reversible friction control and self-cleaning. These uncommon attempts at photo-assisted dynamic morphing extend the possibilities of microfabrication on polymer films and are expected to find new opportunities to create new surface functions in soft materials.