Surface-mediated photoalignment of organic/inorganic nanohybrids

Abstract

Light irradiation provides significant tools for material structuring and processing. In this article, the photo-orientation processes of the organic/inorganic hybrid materials recently achieved in our laboratory are briefly introduced. Irradiation of linearly polarized light to a polymer film containing a photoisomerizabke azobenzene or photocrosslinkable cinnamoyl unit leads to the induction of anisotropic molecular orientations on the surface. This molecular anisotropic surface structure can be transferred to a controlled orientation of nanostructures of organic/inorganic hybrid films at macroscopic scales. Two classes of lyotropic/silica systems have been applied to the photo-orientation procedures, i.e., ordinary surfactant systems and chromonic ones. These processes can be regarded as the extended applications of the so-called command surface systems, which photochemically regulate the molecular orientations of liquid crystals.

Taming Macromolecules with Light: Lessons Learned from Vibrational Spectroscopy

“…Multiple inscription and erasure steps can therefore be combined, although erasure with light leaves out-of-plane anisotropy in the material. [58] Photo-orientation of azobenzenes has interesting application prospects, such as all-optical inscription of waveguides, [60,61] photoalignment of nanostructures in organic/inorganic hybrid films, [62] and command surfaces/ layers, a concept widely applied for controlling the orientation of liquid crystals. [63] Polarized IR spectroscopy has proven powerful for establishing a fundamental understanding of photo-orientation in macromolecules, since it elegantly complements polarized UV-vis spectroscopy and photoinduced birefringence studies by distinguishing the orientation and kinetics of specific chemical groups in the system.…”

“…Multiple inscription and erasure steps can therefore be combined, although erasure with light leaves out‐of‐plane anisotropy in the material . Photo‐orientation of azobenzenes has interesting application prospects, such as all‐optical inscription of waveguides, photoalignment of nanostructures in organic/inorganic hybrid films, and command surfaces/layers, a concept widely applied for controlling the orientation of liquid crystals …”

Magnetically induced orientation of mesochannels inside porous anodic alumina membranes under ultra high magnetic field of 30 T: Confirmation by TEM

“…Many techniques for the alignment of mesochannels have been developed to date, 8), 9) including electrically induced orientation, 10) photo-induced polymer orientation, 11), 12) shear flow, 13) use of anisotropic 14) or modified surfaces, 15), 16) and use of unique synthetic conditions. 17), 18) Recently, the synthesis of mesoporous materials within the regular and straight channels (with a diameter size of generally 200 nm) of porous anodic alumina membranes (PAAMs) has been explored as an element of morphological control.…”