Rikukawa Masahiro

The structural and dynamic properties of a brush-type hydrocarbon copolymer are investigated using first principles molecular dynamics simulations. Two model compounds, one with mainly hydrophilic domains and one with mainly hydrophobic domains, were selected and used in the simulations. A series of radial distribution functions of different groups, such as water-water, sulfonic group-hydrogen, and ether-hydrogen, is obtained to investigate the structure of the whole systems. The radial distribution functions of sulfonic groups, g(s-s)(r), and the structure of water clusters indicate the formation of a well-developed water channel in the studied copolymer. Analysis of proton dissociation reveals that the protons in both systems are not completely dissociated when the number of water molecules per sulfonic group is equal to 4. The low dissociation nature of this copolymer compared with that of Nafion is explained by its intrinsic acid strength and the presence of ineffective hydrogen bonds in the system, where ineffective hydrogen bonds indicate hydrogen bonds that do not contribute strongly to proton transport. The proton conductivity of this copolymer is comparable to that of Nafion, which is ascribed to the formation of good water channels. In addition, the calculated electrical conductivity of the two model compounds shows good agreement with the measured proton conductivity of this copolymer.

We investigated the structure and the swelling behavior of two synthesized hydrocarbon polymer electrolyte membranes, made of multiblock copolymer poly(sulphonate phenylene)-b-poly(arylene ether ketone) with different block ratios, by using small-angle neutron scattering technique. A scattering maximum (ionomer peak) at high-q range (0.1 < q < 0.3 angstrom(-1)) is shown commonly in both dry and wet states, with q being the magnitude of the scattering vector, while it shifts towards low-q region in the wet state due to the swelling of the ionomer domains with water. The swelling effect also results to a second scattering maximum in the middle-q range (0.01 < q < 0.03 angstrom(-1)) because of the water-induced microphase separation. This swelling behavior was confirmed in various water mixtures of normal water and deuterated water with different volume ratios (contrast variation method). The morphology of the wet membranes was analyzed in terms of Hard-Sphere model with Percus-Yervick interference interactions. Our analysis indicated that (i) the hydrated microdomains in the membranes are interconnected, which is the key point to promote the proton conductivity; (ii) the water-induced microphase separation structure and the amphiphilicity of the matrix for embedding the ionomer domains are closely related to the chemical structure of the polymer. (C) 2016 Elsevier Ltd. All rights reserved.

Diblock copolymer ionomers SP1-P2(m-n) with ion exchange capacity (IEC) of 0.96-2.42 meq g(-1) were prepared. The parent diblock copolymers P1-P2(m-n) having various block lengths (m, n) were synthesized via successive catalyst-transfer polymerization of 1,4-dibromo-2,5-di[4-(2,2-dimethylpropoxysulfonyl)phenyl]butoxybenzene (1) and 1,4-dibromo-2,5-hexyloxybenzene (2). The molecular weights were successfully controlled by the feed ratio of the monomer and catalyst, and the molecular weight distribution values were less than 1.32, irrespective of the polymerization degree or polymerization order. Preliminary morphological studies showed that the diblock copolymer ionomers SP1-P2(m-n) had a clear phase separation that could be controlled by the ratios and lengths of the hydrophilic and hydrophobic units. The ionomers showed high proton conductivities with a small humidity dependence, indicating that the clear phase separation formed by the precisely controlled molecular weight and polydispersity index (PDI) of the diblock copolymers enhanced the ionic connectivity and proton conductivity.

L-Proline moieties, which serve as organocatalysts, were tethered on block copolymers that consisted of thermoresponsive poly(N-isopropylacrylamide) and PEG-grafted polyacrylate blocks. The copolymer dissolved in water under the LCST (25 °C), while they formed micelle above the LCST (50 °C). Aldol reactions between an aryl aldehyde and a ketone were conducted in this aqueous solution. The aldol products were obtained in high yield with high diastereo- and enantioselectivity (96% ee). The catalyst solution could be reused up to three times.

Poly(L-lactic acid)/hydroxyapatite (PLLA/HAp) composites were fabricated by in situ polymerization of L-lactide in porous HAp disks, using lipase as a catalyst. The effect of using various lipase species on the molecular weight of the resulting PLLA was investigated, as was the effect of varying the lipase concentration. Lipase CA, derived from Candida antarctica, was found to promote the polymerization of L-lactide in bulk form as well as within porous HAp disks. The in situ polymerization of L-lactide within lipase CA-coated HAp disks at 130°C for 7 days resulted in PLLA/ HAp composites with a PLLA content in the range of 16 to 19 wt.%. The weight average molecular weights of the PLLAs formed in these composites were in the range of 1.6 × 104 to 3.0 × 104 g mol-1 and varied with the lipase CA concentration. The PLLA/HAp composites exhibited a maximum bending strength of 72 MPa and a fracture toughness value of 0.93 MPa m1/2, as estimated by three point bending tests. The cell adhesion and proliferation properties of these materials with osteoblast-like MC3T3-E1 cells suggest that these PLLA/HAp composites have suitably bioactive surfaces. © The Society of Polymer Science, Japan.

Shikimic acid was first isolated in 1885 by Eijkman from the fruit of the Japanese plant Illicium religiosum. Many natural plants contain shikimic acid for biosynthesis as an important intermediate. Roche pharmaceutical uses shikimic acid from star anise as a starting material for production of Tamiflu. However, isolation of star anise from natural resources has been limited. Here we report efficient and new isolation protocol of shikimic acid from Ginkgo biloba leaves utilizing an ionic liquid that dissolves cellulose. Shikimic acid was efficiently extracted and isolated from G. biloba leaves utilizing an ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl), which is able to dissolve cellulose. Using the ionic liquid at 150 ℃ gave an extraction yield of 2.3% w/w for shikimic acid, which was 2.5 times higher than that for methanol at 80 ℃ (0.93% w/w). Meanwhile, an isolation protocol for obtaining shikimic acid in good yield from the IL phase using an anion-exchange resin Amberlite IRA-400 Cl form was established. The SEM micrograph of the leaves after extraction showed a significantly different morphology, with the larger features completely broken down into much smaller structures, indicating that the G. biloba leaves were much more highly dissolved in [bmim]Cl compared to in methanol The present procedure could lead to a convenient supply of shikimic acid, thus enabling production of greater amounts of the antiviral agent Tamiflu. The protocols are also likely to be applicable to other plant leaves, allowing for isolation of greater quantities of other natural products as well as unknown natural compounds.

Oligothiophene derivatives, 4,4′-bis-(2-aminoethylthienyl)-3,4- ethylenedioxythiophene dihydrohalide (AET-EDOT·HX: X = I, Br), were synthesized by Grignard coupling reactions. The hybrid films of oligothiophene and lead halide were fabricated by casting and spin-coating methods. The effect of halogen species on the optical properties of the perovskites was investigated. The X-ray diffraction profiles of (AET-EDOT)PbX 4 cast films indicated that the layered structures were formed by the self-organization. After hybridization of AET-EDOT·HX with PbX 2, new absorption peaks due to the confined excitons were observed at 400 nm for (AET-EDOT)PbBr 4 film, and at 395 nm for (AET-EDOT)PbI 4 film. These results indicated that the diamino-type oligothiophenes were successfully incorporated into the organic-inorganic layered perovskites. AFM images of (AET-EDOT)PbX 4 cast films showed polycrystalline grains, indicating that the polycrystalline structures covered on the substrate surface. © (2012) Trans Tech Publications, Switzerland.

Ni(0)-catalyzed coupling polymerization of 2,5-dichloro-4'-phenoxybenzophenone was investigated by varying the ligand and coligand, temperature, reaction time, and solvent. The weight-average molecular weight (M(w)) of poly(4-phenoxybenzoyl-1,4-phenylene)s (PPBPs) could be controlled by the polymerization conditions and reached a maximum of 4.4 x 10(5) g mol(-1). Sulfonated PPBPs (S-PPBPs) with various M(w)s were prepared with sulfuric acid to study the effect of molecular weight on the chemical and electrical properties of PPBP-based electrolytes. The strong molecular interactions in S-PPBP provided an ion exchange capacity of 2.9 meq g(-1) without loss of high mechanical properties. High molecular weight S-PPBPs had more desirable properties for fuel cell applications. While the swelling ratios and hydration numbers of S-PPBPs decreased with increasing molecular weight, the mechanical strength, proton conductivity, and fuel cell performance increased. S-PPBP also showed anisotropic behavior in the swelling and proton conductivity; such behavior is caused by the rigid-rod nature and the liquid-crystal structure. (C) 2011 Elsevier Ltd. All rights reserved.

An imidazolium-based zwitterion containing two oxyethylene units was obtained as a colorless liquid at room temperature. The equimolar mixture of the liquid zwitterion and lithium bis(trifluoromethylsulfonyl) amide showed an ionic conductivity of over 10(-4) S cm(-1) at 80 degrees C, which was higher than those of mixtures composed of analogous solid zwitterions.

We have developed the porous HAp ceramics with bi-modal pore structure. Using the porous HAp ceramics, HAp/poly-L-lactide (PLLA) hybrids were fabricated by introducing PLLA into the porous HAp ceramics via enzyme polymerization of L-lactide using lipase (lipase PS) as an enzyme. The amount of lipase PS was added 1 and 3 mass% to weight of L-lactide. In order to examine the changes of material properties before and after immersing into the simulated body fluid (SBF), we fabricated three kinds of specimens: i) Porous HAp, ii) HAp/PLLA(1%), iii) HAp/PLLA(3%). The bending strength of the hybrids decreased during immersing SBF up to 28 days. Furthermore, when the hybrids were immersed into the SBF for 4 days, the formation of bone-like apatite occurred on the surface of the specimens.

An ionic liquid having a hydroxyl group, choline bis(trifluoromethylsulfonyl)amide ([N-111(2OH)][N(Tf)(2)]), was synthesized to investigate the effect of hydroxyl groups on the proton transport. 1,1,1-Trifluoro-N-(trifluoromethylsulfonyl)methanesulfoneamide (HN(Tf)(2)) as a proton source was mixed with the choline derivative at various molar ratios. Their thermal properties, viscosities, and ionic conductivities were investigated. [N-111(2OH)][N(Tf)(2)] showed a melting point at 27 degrees C, and its thermal stability was higher than 400 degrees C. The viscosity of [N-111(2OH)][N(Tf)(2)]/HN(Tf)(2) mixtures increased as the acid molar fraction increased. The ionic conductivity of [N-111(2OH)][N(Tf)(2)] was 2.1 x 10(-3) S cm(-1) at 25 degrees C; the ionic conductivity monotonously decreased as the acid molar fraction increased. There was a clear correlation between the ionic conductivity and the viscosity for the mixtures of the choline derivative and the acid. PFG-NMR measurements were carried out to investigate the diffusion behavior of protons. Although the acid and the hydroxyl group were indistinguishable by H-1 NMR, the self-diffusion coefficient of the H-1 of the hydroxyl group and the acid was larger than those of other H-1 nuclei. This difference suggests that a fast intermolecular proton transfer exists between the hydroxyl group and the acid.

Shikimic acid, the starting material in the commercial synthesis of oseltamivir phosphate (Tamiflu (R)), was efficiently extracted and isolated from Ginkgo biloba leaves utilizing the ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl), which dissolves cellulose.

Hybrids of beta-tricalcium phosphate (beta-TCP) and poly(L-lactic acid) (PLLA) have been fabricated, which can be expected to be a novel filler for biodegradable bone grafting. Firstly, porous beta-TCP ceramics have been made of calcium-phosphate fiber synthesized by homogeneous precipitation method. Then, the hybrids have been fabricated by introducing PLLA having high-molecular-weight into the open pores of the porous beta-TCP ceramics. The mechanical property was enhanced, for example, by annealing the hybrids at 140 degrees C for 24 h; the bending strength was 17.1 MPa, which was about 1.5 times that of the porous beta-TCP ceramics. The biocompatibility has been examined using osteoblastic cell, MC3T3-E1, and found to be comparable to that of pure beta-TCP ceramics. (C) 2010 The Ceramic Society of Japan. All rights reserved.

Multilayer-type polymer electrolyte membranes composed of a sulfonated poly(4-phenoxybenzoyl-1,4-phenylene) (S-PPBP) layer and a mono[ poly(propylene oxide)methacrylate] phosphate ester (PPHP) layer were fabricated by solution-casting procedure (Method 1) and hot-pressing procedure (Method 2) in order to suppress methanol permeability of electrolyte membranes. No delamination was observed by SEM measurements of S-PPBP/PPHP interfaces, indicating that PPHP had good adhesive properties to S-PPBP surfaces. The methanol permeability of S-PPBP/PPHP membranes was lower than that of S-PPBP membranes and decreased with increasing the thickness of PPHP layers. The bilayer membrane with 12 mu m PPHP and 40 mu m S-PPBP layers showed a methanol permeability of 2.97 x 10(-7) cm(2) s(-1) in 1 mol dm(-3) methanol aqueous solution at 25 degrees C, which was 13% less than that ofthe S-PPBP membranes. The conductivity of this membrane reached its optimum with values as high as 1.57 x 10(-1) S cm(-1) at 80 degrees C and 90%RH. (C) 2009 Elsevier Ltd. All rights reserved.

Poly[9,9-dihexylfluorene-co-(benzothiazol-2-yl)thiophene-co-9,9'-spirobifluorene] (PF(x)B(y)S(z)) were synthesized by palladium-catalyzed Suzuki coupling reaction. PE(x)B(y)S(z) were characterized by FT-IR,elemental analysis, and (1)H NMR. All the copolymers showed decomposition temperatures above 400 degrees C and glass transition points above 180 degrees C. suggesting that these materials had excellent thermal stability. As the benzothiazolylthiophene content in copolymers was increased, the band gaps of copolymers decreased. All the copolymers exhibited fluorescence peaks in the visible region, and the energy transfer from fluorene to benzothiazolylthiophene units were observed. (C) 2009 Elsevier B.V. All rights reserved.

A series of alternating copolymers consisting of chiral thiophene and fluorene, poly[9,9-dihexylfluorene-alt-(3-{2-[(S)-(+)-1-methyloctyloxy]ethyl}thiophene)] (P1), and poly[9,9-dihexylfluorene-alt-(3-{2-[(S)-(+)-1-methyloctyloxy]ethyl}-2,2'-bithiophene)] (P2), were synthesized by Suzuki coupling method. P1 and P2 were characterized by (1)H NMR spectra and elemental analyses. Both of the copolymers showed clear solvatochromism and circular dichroism in methanol/chloroform mixed solutions. These two polymers had different spacer lengths between the chiral side chains along the main chain. and accordingly the circular dichroism spectra were apparently different. (C) 2009 Elsevier B.V. All rights reserved.

Novel lead iodide-based layered perovskite compounds, which contain fullerene derivatives, N-methyl-2-(4-ammoniumphenyl)-fulleropyrrolidine iodide (AmPF) and N-(n-dodecyl)-2-(4-ammoniumphenyl)fulleropyrrolidine iodide (C12AmPF), in their organic layers were fabricated as thin solid films by spin-coating. The XRD profiles showed that (AmPF)Pbl(4) molecules were arranged in a closer-packing form, compared with (C12AmPF)Pbl(4). The photoluminescence spectra of thin films suggested the presence of energy transfer between C(60) moiety and lead(II) iodide layers, which led to the disappearance of fluorescence peak at 517 nm and the appearance of a new fluorescence peak at 780 nm.(AmPF)Pbl(4) and (C12AmPF)Pbl(4) films exhibited photoconductivity when ultraviolet light was irradiated, and the photocurrent values with applying 1.0 V bias voltage were 1.77 mu A and 1.48 x 10(-2) mu A, respectively. (C) 2009 Elsevier B.V. All rights reserved.