Photoinduced alignment behavior of polymer liquid crystals containing azobenzene moieties in the side chain*

Abstract: Azobenzene-containing polymeric systems are being developed as materials for photonic applications. The present work deals with the photoinduced two-dimensional (2-D) and three-dimensional (3-D) alignment behavior of polymer liquid crystals (PLCs) with azobenzene moieties in the side chain. 2-D alignment of the PLCs was brought about on irradiation of linearly polarized light. The effects of various factors such as experimental conditions and structural parameters of the PLCs on the 2-D alignment behavior have been explored in detail. The response was enhanced by two methods: chemically tailoring structure of the PLCs and physically modifying the alignment procedure. 3-D alignment of the azobenzene moieties was achieved on irradiation of unpolarized light. It was revealed that the azobenzene moieties were aligned along the propagation direction of the irradiation light. Inert mesogens underwent reorientation together with azobenzene moieties in the 2-D as well as 3-D alignment process

Optical switching of nematic liquid crystal by means of photoresponsive polyimides as an alignment layer

Photosensitive polyimides (PIs) as an alignment layer induced optical switching of nematic liquid crystal (NLC) on photoirradiation at 366 nm. The orientation of NLC molecule was changed from homogeneous to homeotropic alignment on photoirradiation with a dc electric field as a bias. The optical switching behavior of NLC was largely affected by the chemical structures of PIs. (C) 1999 American Institute of Physics. [S0003-6951(99)02748-5]open91

Polymerization of propylene with [t-BuNSiMe2Ind]TiMe 2-MAO catalyst systems

ansa-Indenylamidodimethyltitanium complex ([t-BuNSiMe2Ind] TiMe2: 1) was synthesized by one-pot reactions starting from the ligand, MeLi and TiCl4. The structure of 1 was determined by X-ray crystallography and the results obtained revealed that the indenyl ligand coordinate to titanium in an η4-tendency. Propylene polymerization was conducted with 1 in toluene or heptane as solvent at 0°C in the presence of dried methylaluminoxane (MAO) or dried modified MAO (MMAO), which was prepared from the toluene solutions of MAO or MMAO by removing free trialkylaluminium contained. Polymerization behavior was investigated from the consumption rate of propylene in a semi-batch system. The dried MAO/toluene system showed the highest activity without any deactivation. The produced polymer in the dried MAO/toluene system had the highest molecular weight and narrowest molecular weight distribution. The number-average molecular weight of the polymer increased almost linearly with increasing polymerization time accompanied by narrowing molecular weight distribution from 1.42 to 1.37 and the number of polymer chains was almost constant. Thus, it was found that quasi-living polymerization of propylene proceeded. The 13C NMR measurement indicated that 1-dried MAO/toluene produced poly(propylene) with isotactic triad of 40%.

Stereospecific polymerization of propylene with group 4 ansa-fluorenylamidodimethyl complexes

Group 4 [η1:η3-tert- butyl(dimethylfluorenylsilyl)amido]dimethyl complexes [t-BuNSiMe 2Flu]MMe2 (M = Ti, 1; Zr, 2; Hf, 3) were synthesized in a one-pot synthesis starting from the ligand, MeLi and MCl4 (M = Ti, Zr, Hf), respectively. The structures of these complexes were determined by X-ray crystallography and the results obtained revealed that the fluorenyl ligand coordinates to center metal in a η3-manner irrespective of center metal employed. Propylene polymerization was conducted at 0 or 20 °C in toluene by 1-3 combined with dried methylaluminoxane (MAO), which was prepared from the toluene solutions of MAO by removing free trialkylaluminiums, and HNMe2PhB(C6F5)4 in the presence of triisobutylaluminium. The 1-dried MAO system gave the polymer with syndiotactic triad (rr) of 63 0x1.e2fc8p-891t 0 °C, whereas 2 and 3 did not give any polymer in the same conditions. The 2-dried MAO system gave the polymer with the highest syndiotacticity (rr = 97%) at 20 °C, although the activity was low. The 3-dried MAO system did not give any polymer even at 20 °C. When HNMe2PhB(C6F5)4 was used in place of dried MAO at 20 °C, 1 gave almost atactic polymer, while 2 and 3 gave highly syndiotactic one (rr > 90%). These results indicate that the catalytic performance strongly depended on the center metal of the ansa- fluorenylamidodimethyl complexes as well as cocatalysts employed

ヒカリオヨビホウシャセンニヨルポリ-アルファ-メチルスチレンノヨウエキチュウニオケルブンカイニカンスルケンキュウ

京都大学0048新制・課程博士工学博士甲第2144号工博第587号新制||工||422(附属図書館)5742UT51-55-L482京都大学大学院工学研究科高分子化学専攻(主査)教授 東村 敏延, 教授 西島 安則, 教授 今西 幸男学位規則第5条第1項該当Kyoto UniversityDA