宇佐美 清章

We have investigated the effect of alkyl-amine vapor treatment on pretilt angle generation by photo-alignment films of polyimide containing azobenzene in the backbone structure (Azo-PI). By performing alkyl-amine vapor treatment in preparing photo-alignment Azo-PI layers, the controllable range of the pretilt angle was extended at least up to 38° without appearance of threadlike disclination loops. We found that such a high pretilt angle was induced by the photo-alignment layers with a high inclination angle and narrow orientation distribution of the Azo-PI backbone structure in the out-of-plane direction.

<p>Photo-alignment efficiency of polyimides containing azobenzene in the backbone structure (Azo-PIs) is significantly enhanced by performing a simple alkylamine vapor treatment on the precursor (polyamic acid: Azo-PAA) films prior to photo-alignment. This is due to the efficient photo-induced rotation of Azo-PAA backbone structures in the amine-treated films, which are swollen by absorbing alkylamine molecules. In this study, we have examined the relationships between the amine vapor treatmen t time and the thickness of the amine-treated Azo-PAA film, and also between the amine vapor treatment time and the photo-induced in-plane anisotropy of the Azo-PAA and Azo-PI films.</p>

<p>By performing alkyl-amine vapor treatment in preparing photo-alignment layers of polyimides containing azobenzene in the backbone structure (Azo-PIs), the controllable range of the pretilt angle of liquid crystals can be extended at least to 38 without appearance of threadlike disclination loops. In this study, we have investigated the relationship between the average inclination angle of the Azo-PI backbo ne structure and the pretilt angle. We found that the pretilt angle increases with increas ing average inclination angle of the Azo-PI backbone structure.</p>

Recently, we succeeded in improving the controllable range of the pretilt angle of liquid crystal with defect-free alignment by using amine-vapor-treated photoalignment layers of polyimides containing azobenzene in the backbone structure (Azo-PI). The molecular orientation of the Azo-PI photoalignment layers with and without the amine vapor treatment was determined by measuring polarized infrared absorption spectra as a function of the angle of incidence. We found that the average inclination angle of the Azo-PI backbone structures in the amine-vapor-treated film was much higher than that in the untreated film.

ジアミノアゾベンゼンとピロメリット酸から合成されるポリアミック酸（Azo-PAA）の膜に斜めから無偏光紫外光を照射しその後熱イミド化することで、液晶にプレチルト角を誘起するポリイミド（Azo-PI）光配向膜が得られる。このAzo-PAAに側鎖を付与し、その導入量を制御することで、0度から90度の間の様々なプレチルト角を誘起することに成功したので、今回報告する。