Ryuichi Tanaka

Network polymers with cholesteric liquid crystalline order prepared from poly(γ-butyl L-glutamate)-butyl acrylate liquid crystalline system

Abstract Polymer composites consisting of poly(γ-butyl L-glutamate) (PBuLG) and crosslinked poly(butyl acrylate) (PBuA) have been prepared by causing butyl acrylate (BuA) to polymerize in PBuLG-BuA cholesteric liquid crystalline states. The composites exhibited cholesteric organizations in bulk and in swollen states. Microscopic as well as macroscopic swelling behaviour of the composites was examined and was discussed in relation to their crosslink densities. About two-thirds of the PBuLG component could be eliminated from the composites by extraction with either chloroform or dichloroacetic acid (DCA), and the extracted composites still possessed cholesteric organizations. Practically complete removal of the PBuLG component from the composites was achieved by hydrolytic extraction with a DCA-HCl mixture. The PBuA polymer networks thus obtained exhibited no cholesteric organization, but once again the cholesteric organizations emerged when the networks were swollen in solvents. This observation was interpreted in terms of the topology of the networks constructed in cholesteric liquid crystalline states.

Nucleophilic attack on halogeno(phenyl)acetylenes by halide ions

Nucleophilic reactions between halogeno(phenyl)acetylenes and halide ions, ArCCX + Y–, where Ar = C6H5 or p-ClC6H4, X = Cl or Br, and Y = Cl or Br, have been examined. Halogen exchange of the Finkelstein type was observed for the first time in acetylene halides in anhydrous dimethyl sulphoxide when X = Br and Y = Cl. This exchange did not occur with other X–Y combinations. In the presence of up to 20% water in dimethyl sulphoxide, or under aqueous–organic phase-transfer catalytic conditions, nucleophilic addition (formally of HY) took place for all the X–Y combinations studied. In the additions, the nucleophile Y– invariably attacked the carbon to which the phenyl group was bound. The mode of HY addition was stereospecifically trans; accordingly, the resulting dihalogenostyrenes always had the (Z)-1,2-dihalogeno-configuration.

Heterogeneous network polymers: 7. Cholesteric liquid crystal structure of poly(glutamic acid) fixed by crosslinking

Abstract The phase structure of the heterogeneous network polymers prepared from poly(glutamic acid) (PGA) and poly(oxyethylene glycol) ( PEG , M n = 302 ) was investigated by polarizing microscopy. The solid films had a layered structure comprising cholesteric liquid crystal domains. In each domain α-helices of PGA are aligned nearly parallel to the film surfaces. The cholesteric liquid crystal structure was not destroyed even when the films were heated in dimethylformamide (DMF) at 100°C for a week in spite of the fact that DMF can easily dissolve PGA and PEG at 50°C. This suggests that the cholesteric liquid crystal structure formed in the concentrated solutions of PGA, PEG and DMF is perpetuated by crosslinking.

Poly(L-glutamic acid)-poly(oxyethylene glycol) systems: Perpetuated cholesteric liquid crystal structures in noncrosslinked and crosslinked solid films

Abstract The origin of the peculiar microphase structures of so-called PGA/PEG polyblends and PGA-PEG heterogeneous network polymers cast from dimethylformamide or dioxane-water was studied by means of phase diagrams, infrared spectra, x-ray diffractions, polarizing optical microscopy, and small-angle light scattering. It was demonstrated that in such solvents, poly(ethylene oxide) (PEO) or poly(oxyethylene glycol) (PEG) can fill the interstitial space between the parallel arrays of the α-helices of poly(L-glutamic acid) (PGA) and become an integral constituent of the lyotropic cholesteric liquid crystals. Such structures were found to be perpetuated in the solid films of both the noncrosslinked PGA/PEO and the crosslinked PGA-PEG after the solvent was evaporated. The dynamic mechanical behavior of the solid films was consistently interpreted on the basis of such phase structures.

Intermolecular trapping of vinyl nitrene equilibrated with azirine

Thermal decomposition of 3-azido-1,2-benzo-1,3-cycloheptadiene (1a) gave the fused azirine (2a), which gave pyrrolobenzocycloheptadien (3a) on heating with dimethyl acetylenedicarboxylate (DMAD). Thermolysis of 1-azidoindene (1b), did not give the azirine, but gave the fused pyrrole (3b) by decomposition in the presence of DMAD. These results provided firm evidence for intermediacy of vinyl nitrenes

Topological Polymer Networks Retaining Cholesteric Liquid Crystalline Order Without Mesogen

Abstract Crosslinked poly (butyl acrylate) which possesses cholesteric liquid crystalline order has been prepared. First, butyl acrylate was caused to polymerize in a poly(γ-butyl L-glutamate)—butyl acrylate liquid crystalline state. Then, the poly(γ-butyl L-glutamate) component was eliminated from the system by hydrolytic extraction. The network polymer thus obtained exhibited cholesteric liquid crystalline organization when it was swollen in solvents.