Optical alignment control of polyimide molecules containing azobenzene in the backbone structure

Pretilt angle control of liquid crystal molecules by photoaligned films of azobenzene-containing polyimide with a different content of side-chain

“…2 as a function of the side-chain content x ͑DAB content xЈ͒. 35 First, the pretilt angle decreases to ϳ1°by introducing a small amount of the side-chain structure. Since this band is assigned to the C-N-C stretching vibration of imide ring The photoinduced in-plane anisotropy ͑Q ⌽ ͒ of the Azo-PI-I films decreases linearly with increasing x. Interestingly, the data points for the Azo-PI-II films lie on the same straight line.…”

“…4͒. 35 This is a cause for the initial slight decrease in the pretilt angle. 43 Thus, the initial slight decrease in the pretilt angle can be attributed to a decrease in the inclination angle of the polyimide backbone structure at the Azo-PI-I film/LC interface.…”

“…35 First, the Azo-PAA film was exposed to linearly polarized light ͑LP-L͒ at normal incidence to induce in-plane anisotropy efficiently. Photoalignment treatment was performed on the Azo-PAA films, using a 500 W deep UV lamp ͑Ushio Inc. UXM-501MD͒ as the light source.…”

“…Photoalignment treatment was performed on the Azo-PAA films, using a 500 W deep UV lamp ͑Ushio Inc. UXM-501MD͒ as the light source. This oblique angle irradiation induces inclined alignment of the Azo-PAA backbone structure toward the propagation direction of the UP-L. 35 Then, the films were thermally imidized at 250°C for 1 h in a nitrogen atmosphere. 35 First, the Azo-PAA film was exposed to linearly polarized light ͑LP-L͒ at normal incidence to induce in-plane anisotropy efficiently.…”

Light-Tunable Solvent Drying in Photo-Responsive Solution Coatings

“…1).The non-planar cis form shows a higher surface energy and thus is more hydrophilic than the planar trans form [4] Furthermore, the long axis of azobenzene moiety is known to become oriented perpendicular to a polarized direction of light due to its angular-selective absorption. Based on these unique characteristics, extensive studies have been performed for photo-induced rapid mass transfer, [5] morphology control in phase separating blends, [6] light-guided reversible motion of a liquid droplet, [4] anisotropic molecular orientation, [7] structural change in monolayer on a liquid surface, [8,9] and for creating photosensitive surfactants [10] and photo-rheological fluids with light-tunable viscosity. [11] However, little attention has been paid to drying kinetics of photo-responsive solutions exhibiting the orientation and=or structural change on a molecular level.…”