Responsive microstructures on organic–inorganic hybrid films

Micro-periodic structures exhibiting shape
memory have been fabricated on organic–inorganic hybrid
films. The microscale structures are obtained by forming
wrinkles via buckling of the stiff surface layer. The surface-
modified layers are obtained by surface photopolymerization
or by oxidation of the hybrid films. The
microscale structures are spontaneously formed by the
shrinkage of the underlayer via gelation. The surface
microstructures on titania- or silica-based films with
hydrophilic swellable polymers exhibit a humidity
response, i.e., a shape memory effect. This is observed
when the surface microstructure disappears and is subsequently
recovered with cyclic variation of the surrounding
humidity. Micro-rolls are also fabricated by the selective
swelling of surface-modified layers.