Exposure of positive-type polyimide (PI) to linearly polarized deep UV (DUV) light (257nm) induced homogeneous alignment nematic liquid crystals. The state changed markedly at a particular energy the light. Measurement absorption spectrum and retardation change generated in PI films by irradiation showed that anisotropic was caused new mechanism, photodepolymerization main chains parallel electric field DUV light.We monodomain exposing direction perpendicular DUV, its condition suddenly...

Abstract Crystalline 2,5‐distyrylpyrazine (DSP) was found to polymerize into a linear high polymer with extremely crystallinity by the action of sunlight or ultraviolet light. Based on this discovery, photopolymerizability related diolefins having general formula, trans , ‐Ar′CHCHArCHCHAr′ surveyed. As result, 1,4‐bis[β‐pyridyl‐(2)‐vinyl]benzene (P2VB) in same way as DSP. The polymers polymerized, showed melting temperature (>330°C) and were soluble only strong acids. structure...

Abstract A new preparative route to photocrosslinkable polymers in which the are produced directly from polymerization of vinyl monomers having groups has been investigated. The photosensitive resins thus have higher sensitivity and resolution than conventional resins. were synthesized esterification vinylphenols or β‐chloroethyl ether with cinnamic acid, β‐styrylacrylic their homologs, etherification hydroxychalcones. Homopolymerizations these copolymerizations other comonomers investigated...

Abstract

Abstract The polymerization mechanism of trans , ‐2,5‐distyrylpyrazine (DSP) has been investigated and some crystal changes along with the process have observed through polarizing microscope x‐ray diffraction pattern. Information obtained on active species, reaction type, other factors such as light intensity, temperature, or crystalline state. DSP occurs only in solid state by photoirradiation. Reduced viscosity increases gradually increase conversion sharply above 80% conversion....

Abstract 2,5-Distyrylpyrazine(C20H16N2), which has photo-polymerizability in the crystalline state, crystallizes orthorhombic system with cell dimensions of a=20.638, b=9.599, and c=7.655 Å, including four molecules unit cell. The space group is Pbca. structure been determined by direct method refined block-diagonal-matrix least-squares using three-dimensional data. not planar; average plane pyrazine ring makes a dihedral angle 12.09° that benzene ring. are spaced c-translation forming an...

Abstract The solid‐state photopolymerization of phenylene diacrylic acid (PDA) and its derivatives was studied as an application photodimerization cinnamic to corresponding bifunctional molecule which has two units in a single molecule. p ‐ m ‐PDA, their esters amides were prepared investigated with respect photopolymerizability. Many them have been found polymerize into linear high polymers the cyclobutane rings main chain on irradiation by ultraviolet or visible light. polymerization...

Abstract Further work on the polymerization of 1,3‐cyclohexadiene by action Zieglertype catalysis and cationic initiation has been carried out polymers with an inherent viscosity 0.1–0.19 have obtained consistently. Dehydrogenation poly‐1,3‐cyclohexadiene halogenation followed pyrolysis given good conversion to a polyphenyl which some units are incompletely aromatized. This polymer very heat stability but is not useful for plastic purposes.

EZ-Photoisomerization has been attained for several kinds of salts α,β-unsaturated carboxylic acids with amines. This photoreaction proven to be an effective method preparing (Z)-isomers from ammonium (E)-α,β-unsaturated carboxylates. The isomerizability is strikingly altered upon changing the group, which implies that crystal structure affected reactivity a considerable extent. However, cavity in found have less influence than expected on isomerizability. A further detailed study concerning...

Abstract (±)-1,2-Diphenylethylenediamine (DPEDA) was efficiently resolved by the fractional crystallization of its diastereomeric salts with optically active mandelic acid. 1H-NMR spectrum N-monoacylated DPEDA an derivatizing agent showed that thus obtained pure.

Abstract Changes in crystal structure during polymerization and oligomerization of 2,5‐distyrylpyrazine have been investigated by x‐ray crystallography. The polymer the oligomer as obtained are three‐dimensionally oriented, directions three axes resultant crystals coincide with those original crystal. space group products also agrees that monomer. It is concluded approximately duplicate molecular arrangement monomer mechanism discussed on basis structures.

We fabricated sheets consisting of aligned electrospun polymer nanofibers embedded with semiconductor nanorods (NRs) and confirmed the production polarized fluorescence emission. Electrospun NRs were rolled around a drum to form sheet in which each nanofiber was parallel rotation direction. The thickness polarization ratio 1.5 μm 0.6, respectively. also examined how electrospinning parameters affected sheet.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiastereoselective ring-opening aldol-type reaction of 2,2-dialkoxycyclopropanecarboxylic esters with carbonyl compounds. 1. Synthesis cis 3,4-substituted .gamma.-lactonesShigeru Shimada, Yukihiko Hashimoto, Atsushi Sudo, Masaki Hasegawa, and Kazuhiko SaigoCite this: J. Org. Chem. 1992, 57, 26, 7126–7133Publication Date (Print):December 1, 1992Publication History Published online1 May 2002Published inissue 1 December...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and selective molecular recognition of a macrotricyclic receptor having crown ether cyclophane subunits as binding sitesKazuhiko Saigo, Nobuhiro Kihara, Yukihiko Hashimoto, Ru Jang Lin, Hiroshi Fujimura, Yoshihiro Suzuki, Masaki HasegawaCite this: J. Am. Chem. Soc. 1990, 112, 3, 1144–1150Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January...

The photochemical behaviour of fifteen derivatives head-to-head coumarin dimers has been investigated. photocleavage the cyclobutane rings in these compounds solution occurs on irradiation with light wavelength 277 ± 10 nm to give two molecules via symmetric fission and/or 2,2′-dihydroxystilbene and fumaric (and maleic) acid asymmetric fission. direction photofissions is primarily affected by basic structure dimer derivative, proceeding exclusively retention ring when derivative a stable...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTopochemical double photocyclodimerization of the 1,4-dicinnamoylbenzene crystalMasaki Hasegawa, Kazuhiko Saigo, Toru Mori, Hirofumi Uno, Masao Nohara, and Hachiro NakanishiCite this: J. Am. Chem. Soc. 1985, 107, 9, 2788–2793Publication Date (Print):May 1, 1985Publication History Published online1 May 2002Published inissue 1 1985https://pubs.acs.org/doi/10.1021/ja00295a035https://doi.org/10.1021/ja00295a035research-articleACS PublicationsRequest...