陸川 政弘

The relationships between morphology and proton conduction for Nafion membranes and hydrocarbon-type proton exchange membranes, namely, sulfonated poly(arylene ether ether ketone) (S-PEEK) and sulfonated poly(arylene ether sulfone) (S-PES), were investigated by small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The direct simultaneous observation of surface morphology and active regions of proton conduction on membranes by combined high-resolution AFM phase imaging and an electrochemical technique at controlled humidity provided significant morphological information, particularly for the hydrocarbon-type membranes that exhibit few or no features on SAXS profiles. For the Nafion membranes, the active proton paths became denser and congregated with each other at over 60% RH, resulting in the formation of well-connected networks. For the hydrocarbon-type membranes, however, only the relatively small and dispersed proton paths were observed, which showed no significant change even as water content increased. We have demonstrated that the differences in microscopic morphology between the Nafion and hydrocarbon-type membranes are associated with the differences between their macroscopic proton conductivities. (C) 2008 Elsevier Ltd. All rights reserved.

AC-mode atomic force microscopy (AFM) and electrochemical methods were used to identify the proton conducting regions of Nation membrane. It was found that the surface of Nafion membrane was constructed of small hydrophobic granular domains and that protons passed through the hydrophilic regions formed in the interstices between those domains.

Poly(L-lactide) (PLLA) has been synthesized by ring-opening bulk polymerization Of L-lactide in porous hydroxyapatite (HAp) matrix without any additional catalyst, and this hybridizing process directly provided artificial bone materials. The obtained PLLA/HAp composites had enough mechanical properties with a bending strength of 53.7MPa, which was 2.3 times stronger than porous HAp, and showed excellent biocompatibility for clinical applications.

Two-dimensional layered perovskite compounds, (CnH2n+1NH3)(2)(CH3NH3)(m-1)PbmX3m+1 (n = 2, 3, 4, 6, and 10; X = Cl Br, and I; in = 1, 2, and 3) were systematically prepared. The influences of the barrier-size, halide species, and well thickness of the perovskite thin films on the quantum confinement structures were investigated. The layered perovskite films showed a strong and clear absorption peak due to excitons confined in inorganic quantum-wells. The exciton peak shifted to lower energy as the halide species was changed from Cl to Br and I. Furthermore, fine multilayer perovskite compound films were prepared by varying the spin-coating conditions.

A series of poly(thiophene)s, poly(3-(2-benzothiazolyl)thiophene) (PBTT) and poly(3-(2-benzothiazolyl)oxyethyl thiophene) (PBTOET), containing a benzothiazole moiety in the side chain have been synthesized by a cross-coupling reaction using Ni catalyst. PBTT and PBTOET were characterized by FT-IR and H-1-NMR spectra. Both polymers showed fluorescence peaks in the visible region. The HOMO and LUMO energies were estimated by cyclic voltammetry. PBTT was more suitable as a hole transporting material than PBTOET. The turn-on voltages of PBTT and PBTOET single layer EL devices were 5.0 V and 6.5 V, respectively.

We study the layer-by-layer assembly and properties of polyelectrolyte multilayers containing cationic and anionic polythiophene derivatives, poly-2-(3-thienyloxy)propyltriethylammonium chloride (PTPA), poly(thiophene-3-acetic acid) (PTAA), and poly(sodium-2-(4-methyl-3-thiehyloxy)ethane sulfonate) (P-SMTE). These polymers were synthesized by chemical oxidation with FeCl3 and soluble in aqueous media. Two types of multilayers have been prepared by sequential adsorption of polyanions and polycations on charged surfaces: PTPA/PTAA and PTPA/P-SMTE. The linear relationship of the UV-vis adsorption spectra and QCM observed in these multilayer systems indicated that each layer was successfully deposited to form layer-by-layer films. FT-IR results also revealed that the multilayer structure was formed by electrostatic interaction.

A regioregular polythiophene beating an optically active substituent at the 3-position of thiophene ring, Head-to-Tail poly(3-[2-((S)-1-methyloetyloxy)ethyl]thiophene) (HT-P(S)MOET), was synthesized using highly reactive zinc. HT-P(S)MOET had more than 95% Head-to-Tail coupling with a Mw of 3.72 x 10(4) (Mw/Mn = 1.20), as estimated by H-1-NMR spectroscopy and gel permeation chromatography. HT-P(S)MOET had strong negative Cotton effect at about 560 and 6 10 nm and positive Cotton effect at about 490 nm. The presence of circular dichroism effect shows that the chirality of side chains induces the optical activity in poly(thiophene) main chains. The Langmuir-Blodgett films of HT-P(S)MOET exhibited well-defined layer structure and unique optical properties.

Actuators based on hydrocarbon polymer electrolyte membranes having phosphoric acid groups were fabricated to investigate the correlation between the chemical properties and the actuation. The bending size and velocity of actuation were measured and compared with the values for fluorocarbon polymers, Nafion(R)-based actuators. The actuators were fabricated by coating polymer electrolyte membranes with gold using dichlorophenanthrolinegold (III) chloride. The actuators bent toward the anode when the applied voltage was over 1 kV. Nafion(R)-based actuators reached the maximum displacement size within 1 second, while the hydrocarbon polymer-based actuators took over 60 seconds. The difference in the velocity of actuation was caused by the difference in the proton conductivity of polymer electrolyte membranes. The maximum displacement size of hydrocarbon polymer-based actuators was nearly equal to that of Nafion(R)-based actuators.

In polyacetylene and polydiacetylene oligomers, photoluminescence (PL) is induced from the dipole-forbidden state by vibronic coupling. The assumption that the PL in polythiophene (PT) and poly(p-phenylene vinylene) (PPV) also includes this induced component, consistently explains many experimental results. In this work, we focus on the temperature dependence of the time-integrated and time-resolved PL spectra of a PT derivative and unsubstituted PPV, and demonstrate the validity of the above model for their temperature dependence. Applying this model to the hitherto unresolved drastic PL spectral change of unsubstituted PPV, we propose that the spectral change and the spectral shape itself can be understood as resulting from a contribution to the PL from the 2A(g) state coupled with a change in the ordering of the 2A(g) and the 1B(u) states at low temperatures.

Polycondensed thin films which had a high-ordered structure were fabricated from dicarboxylic acid and diamines using N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) as condensing agents by a self-assembly method. In this Study, adipic acid (ADA) or 9,11-docosadiyn-1,20-dicarboxylic acid (DDyDA) were selected for dicarboxylic acid, and 4,4'-diaminodiphenylmethane dihydrochloride (DAM) for diamine parts. UV-vis and quartz crystal microbalance (QCM) measurements were used to monitor the layer-by-layer deposition process. FT-IR reflection absorption spectroscopy (Fr-IR-RAS) was also carried out in order to confirm the polycondensation of monomers. These results indicated that 14 dicarboxylic acid and diamines were alternately deposited and polymerized with condensing agents on nano-scale. In addition, polydiacetylene network was successfully incorporated in DDyDA system by gamma-irradiation due to the high ordered structure. (c) 2004 Elsevier B.V. All rights reserved.

The layered perovskite. (RNH3)(2)PbX4 (R = alkyl group, X = halogen), which contained the fullerene ammonium derivative, N-methyl-2-(4-aminophenyl)-fulleropyrrolidine iodide (AmPF), in the organic layers, was fabricated as a thin solid film. X-ray diffraction measurement of the obtained films revealed that AmPF molecules were introduced to the organic layers, however, the obtained film was heterogeneous. The homogeneous perovskite films were fabricated by addition of dodecylammonium iodide as a supporting material to AmPF. It was found that the layered structures of two-dimensional perovskites changed depending on the rate of AmPF in the organic ammonium layers from the results of X-ray diffraction. UV-vis absorption spectra of the films were also changed by incorporation of AmPF molecules. By increasing the rate of fullerene, new peak at 560 nm was appeared while the exciton peak at 511 nm of the conventional layered perovskite diminished. This suggested that the exciton binding energy was transported from the exciton state of the conventional perovskites to the lower energy state formed by fullerene derivatives in the organic layers. (c) 2004 Elsevier B.V. All rights reserved.

A low-dimensional organic-inorganic perovskite compound, (C4H8N2H4)(2)PbBr6 center dot 2H(2)O, was synthesized from cyclic amines and PbBr2 by using a hydrothermal reaction. The versatile optical properties caused by the quantum confinement structure were investigated.

New proton-conducting polymer electrolyte membranes having phosphoric acid groups have been systematically synthesized. These homopolymers and copolymers were prepared by a conventional radical polymerization and a copolymerization with acrylonitrile or styrene or similar materials. The phosphoric acid groups can be cross-linked by heat treatments at 100 ° C, and hence their membranes showed excellent mechanical properties and chemical stability. Measurements of the water absorption and differential scanning calorimetry revealed that the copolymer membranes absorbed smaller amounts of water, which is freezing water under 90% RH, compared with the sulfonated polyelectrolyte membranes. The proton conductivity of the P-PHM membranes hydrated was measured to be 5.0 x 10(-3) S cm(-1) at 100 ° C. This value was usually maintained up to 160 ° C. Dried homopolymer membranes and copolymer membranes were also examined for the water absorption and proton conductivity. It was found that the copolymerization with acrylonitrile provided good film-forming properties, thermal stability, and useful control of the physical and electrochemical properties. © 2004 Elsevier B.V. All rights reserved.

Well-ordered layered structures prepared by the self-assembly method using condensing agents better facilitate the gamma-ray polymerization of diacetylene units.

Two-dimensional and multi-layered perovskites, [NH3(CH2)(12)NH3] PbBr4 and [NH3(CH2)(12)NH3](CH3NH3)(n-1)PbnBr3n+1, with a quantum confinement effect have been naturally formed by intercalating lead bromide into organic alkyldiammonium bromide frameworks.

Phenethylammonium-based perovskites, which can be regarded as a semiconductor/insulator multiple quantum well consisting of lead halide semiconductor layers sandwiched between phenethylammonium insulator layers were prepared. To investigate the effects of the electronic state and the orientation of organic insulator layers on the optical properties of layered perovskites, fluorine substituted analogues were also prepared. The structure and optical properties were investigated by the XRD, UV-Vis absorption, and fluorescence measurements. The exciton absorption peak was shifted by the substitution of fluorine atoms in organic ammonium compounds. It became clear that the optical properties of two-dimensional perovskite compounds were controlled by the substitution of fluorine atoms. (C) 2004 Elsevier B.V. All rights reserved.

High-performance composites of poly(4-vinylpyridine-co-styrene) copolymer (P4VPy-St) and polyamic acids (PAA) were prepared by in-situ polymerization. High-performance composites could be obtained from a polymer pair that has an attractive interaction such as a hydrogen bonding interaction. The aggregation of the resulting polyimide (PI) took place easily in the P4VPy-St/PI composite film during the stepwise heat-treatment of the P4VPy-St/PAA composite film to convert PAA to PI. This was because of the disappearance of the carboxyl group due to the imidization of PAA. In this study, free carboxylic acid groups were introduced into the side chains of PI in order to improve the mechanical properties of P4Py-St/PI composites, and the carboxyl group content dependence of the tensile strength of the resulting composite films was investigated. The tensile strength of the resulting composite films increased with increasing carboxyl group content in PI. The hydrogen bonding interaction between the pyridine moiety in the P4VPy-St copolymer and the carboxyl group introduced into PI greatly enhanced both the compatibility and the tensile strength of the composite films.

Preparation and characterization of two-dimensional zirconium phosphonate derivatives in either crystalline or amorphous forms have been investigated. Composite zirconium phosphonates in single crystal phase have also been investigated and characterized by XRD and P-31-MASNMR. These compounds are lamellar structures comprising zirconium phosphates or organophosphonates. The hydroxyl groups or sulfomethyl groups are bonded through the phosphorous atoms to an inorganic framework made of oxygen and zirconium atoms. Compounds were characterized for their proton-conductivity as a function of temperature and relative humidity.

The structure and optical properties of a lead halide organic-inorganic perovskite compound containing an (R)-2-octylammonium cation have been investigated in order to confirm the construction of an optically active quantum well. As in the case of the general alkylammonium systems, a spin-coated film of the compounds took the form of a two-dimensional quantum confinement structure, and had stable excitons at room temperature. The polycrystalline film exhibited a definitive Cotton effect in inorganic and exciton absorption regions. The introduction of (R)-2-octyl ammonium into the organic layer easily enabled us to render the organic-inorganic multiple quantum well optically active. [DOI: 10.1143/JJAP.42.L698].

Time-resolved photoluminescence (PL) measurements on highly ordered and disordered films of a polythiophene (PT) derivative were compared. Although delocalization lengths of π electrons and the strengths of interchain interaction are quite different between the two films, a biexponential decay and a change in spectral shape, from one with a large 0-0 transition to one with a large 0-1 transition, were commonly observed. Therefore, we conclude that PL spectra of PT consist of two components having different spectral shapes and different lifetimes, and that these components originate from intrachain odd- and even-parity states that are coupled by electron-phonon interaction. This model explains the greatly reduced fluorescence yield for the ordered film as well as the time-resolved PL measurements. © 2003 The American Physical Society.

Time-resolved photoluminescence (PL) measurements on highly ordered and disordered films of a polythiophene (PT) derivative were compared. Although delocalization lengths of pi electrons and the strengths of interchain interaction are quite different between the two films, a biexponential decay and a change in spectral shape, from one with a large 0-0 transition to one with a large 0-1 transition, were commonly observed. Therefore, we conclude that PL spectra of PT consist of two components having different spectral shapes and different lifetimes, and that these components originate from intrachain odd- and even-parity states that are coupled by electron-phonon interaction. This model explains the greatly reduced fluorescence yield for the ordered film as well as the time-resolved PL measurements.

Thin films of lead iodide based perovskites [p-F(C6H5)C2H4NH3](2)(CH3NH3)(m-1)PbmI3m+1 (m=1, 2) with different inorganic well thickness using p-fluorophenethylammonium as an organic cation were systematically prepared, and the structure and optical properties were investigated. X-ray diffraction patterns demonstrated that the spin-coated film was highly oriented with the c-axis perpendicular to the substrate surfaces and that the control of the inorganic layer thickness in layered perovskites can be achieved by changing the ratio of the two organic amines and lead iodide. When the feed ratio of p-fluorophenethylammonium salt, methylammonium salt, and lead iodide was 2:3.5:3, the bilayer structure was formed. Using p-fluorophenethylammonium instead of alkylammonium as an organic cation, the spin-coated film with high crystallinity was obtained.

Aromatic ammonium-based perovskites and fluorine substituted analogues were prepared. The effects of the electronic structures of aromatic ammonium containing fluorine on the optical properties of layered perovskites were investigated by the XRD, UV-Vis absorption, and fluorescence spectrum measurements. The absorption peaks were shifted by the substitution of fluorine atoms in organic ammonium compounds. It became clear that the optical properties of two-dimensional perovskite compounds were controlled by the substitution of fluorine atoms.

Regioregular poly(thiophene) derivatives with liquid crystal moiety, poly(3-[2-(4-fluorobenzyloxyethyl)]thiophene) (HT-PFBET) and poly(3-[2-benzyloxyethyl]thiophene) (HT-PBET), were synthesized using cross-coupling reaction according to the Rieke method. Thermochromism of HT-PFBET and HT-PBET was studied by electronic absorption measurements. HT-PFBET gave rise to a clear isosbestic point, while HT-PBET exhibited no isosbestic point with increasing temperature. This is due to a morphological effect induced by fluorine atoms.

The template-guided enzymatic polymerization of conducting poly(aniline) particles was investigated. In order to clarify the role of templates in this polymerization, various template polymers such as poly(ethylene oxide) (PEO), polyvinyl alcohol) (PVA), polyvinyl pyrrolidone) (PVP), and poly(sodium 4-styrenesulfonate) (SPS) were used in this study. The enzymatic synthesis of poly(aniline) was successful with a stoichiometric amount of hydrogen peroxide and a catalytic amount of the enzyme (horseradish peroxidase). The chemical structures of template polymers provided difference in particle size of obtained poly(aniline).

Formation of metal complexes from fullerene derivative and phthalocyanine (Pc) derivative was investigated. UV-Vis spectra of C-60 substituted with cyano group (C60CN) and phthalocyaninato iron(II) substituted with tert-butyl groups (FePcTB) showed charge transfer interaction in 1-chloronaphhtalene. The metal complex was synthesized by refluxing o-dichlorobenzene (ODCB) solution of C60CN and FePcTB. TOF-MS spectra indicated that the complex was composed of C60CN and FePcTB with mole ratio of 2/1.

Copolymers of acid phosphoxyethyl methacrylate (PHM) and 2,2,2-trifluoroethylacrylate (TFEA) were synthesized in order to construct hydrophilic and hydrophobic domains as well as Nafion(R) membrane. Thermal decomposition temperatures of PHM-TFEA copolymers were about 250 degreesC, which showed sufficient thermal stability for polymer electrolyte fuel cells (PEFC). Water uptake of these copolymers was higher than that of Nafion 115 under low relative humidity, and proton conductivity of these polymers exhibited about 10(-3) S cm(-1) under 90% relative humidity at 80 degreesC.

Polymeric thin films which had a high-ordered structure were fabricated from adipic acid (ADA), 4,4'-diaminodiphenylmethane dihydrochloride (DAM), and N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) as condensing agents by a self-assembly method. UV-Vis and quartz crystal microbalance (QCM) measurements were used to monitor the layer-by-layer deposition process. FTIR reflection absorption spectroscopy (FTIR-RAS) was also carried out in order to confirm the polymerization of monomers. The surface morphology of the films was investigated with an atomic force microscope (AFM). These results indicated that ADA and DAM were alternately deposited and polymerized with condensing agents on nanoscale.

Poly(4-phenoxybenzoyl-1,4-phenylene) (PPBP), which has high thermal stability and mechanical properties, was phosphonated by the three-step reaction. The phosphonated PPBP (P-PPBP) was characterized by FT-IR, H-1-NMR, elemental analysis, and ICP emission spectroscopy. The thermal and electrical properties of P-PPBP were also investigated. The P-PPBP film containing 40 mol % phosphonic acid groups showed a proton conductivity of about 10(-4) S cm(-1) at 90 %R.H.

Poly(3-(perfuorohexyl)thiophene) (PFHT) was synthesized from 2, 5-dibromo-3-(perfluorohexyl)thiophene via Grignard metathesis method. Obtained polymer was dissolved in a wide variety of organic solvents such as chloroform, tetrahydrofuran, and o-dichlorobenzene. Transition temperatures of PFHT were observed at 54 C due to melting of perfluorohexyl groups. Electron-withdrawing effect of C-F bonds and weak interaction among the side chains were observed as shorter maximum absorption wavelengths. Stable monolayers of PFHT were formed on a water subphase due to strong hydrophobicity and the weak interactions of the perfluorohexyl groups.

This paper presents an overview of the possibility and problems of new proton-conducting polymer electrolyte membranes based on hydrocarbon polymers. Due to their chemical stability, high degree of proton-conductivity, and remarkable mechanical properties, perfluorinated polymer electrolytes such as Nafion^®, Aciplex^®, Flemion^®, and Dow membranes are some of the most promising electrolyte membranes for polymer electrolyte fuel cells. A number of reviews on the synthesis, electrochemical properties, and fuel cell applications of perfluorinated polymer electrolytes have also appeared. While perfluorinated polymer electrolytes have satisfactory properties for a successful fuel cell electrolyte membrane, the major drawbacks to large-scale commercial use involve high cost and low proton-conductivities at high temperatures and low humidities. Presently, one of the most promising ways to obtain high-performance proton-conducting polymer electrolyte membranes is the use of hydrocarbon polymers for the polymer backbone. The present paper attempted to summarize the synthesis, chemical and electrochemical properties, and fuel cell application of new proton conducting polymer electrolytes based on hydrocarbon polymers that have been made during the past decade.

Two kinds of polymers were fabricated and tested as candidates of proton-conducting membranes for polymer electrolyte fuel cell (PEFC) applications. Poly benzimidazole (PBI) and poly(4-phenoxybenzoyl-1,4-phenylene, Poly-X 2000) (PPBP) were sulfonated and characterized as proton-conducting membranes. PBI was sulfonated as PBI-PS (propanesultone) and PBI-BS (butanesultone). PPBP was prepared at various sulfonation levels. Proton conductivities were measured at 60-160 degreesC. Power output characteristics of both polymers were measured by using commercial Pt/C electrodes. (C) 2002 Elsevier Science B.V. All rights reserved.

Organic-inorganic semiconductor heterostructures have been successfully fabricated by incorporating a polydiacetylene backbone into layered perovskite compounds by photopolymerization. The gamma-ray irradiation caused polymerization of aminodiacetylene cations, RNH3+, where R=CH3(CH2)(13)C=C-C=CCH2, in the solid salts of (RNH3)(2)PbBr4.

Novel organic-inorganic hybrid compounds, C10H10N2PbBr4 and C10H22N2PbBr4 were prepared and characterized by X-ray and optical measurements. The result of single crystal X-ray analysis showed that the inorganic region of C10H10N2PbBr4 consisted of one-dimensional chains of line-sharing PbBr6 octahedra, whereas that of C10H22N2PbBr4 consisted of two-dimensional sheets of corner-sharing PbBr6 octahedra. Each crystal exhibited an excitonic band at 307 nm for C10H10N2PbBr4 and 383 nm for C10H22N2PbBr4, which is attributed to the excitonic states of low-dimensional inorganic structures. These results indicate that the dimensional structure of these compounds can be systematically controlled by changing the chemical structure of organic ligands.

Organic-inorganic layered perovskite compounds described by (RNH3)(2)MX4 [R: alkyl group, M: divalent metals, X: halogen] were reported to form self-organized quantum-well structures. In this study, we aimed to synthesize novel organic-inorganic self-organized compounds with quaternary ammonium ions instead of primary alkylammonium ions. New compounds, [(C12H25)(2)(CH3)(2)N]PbBr2 (DLDMPbBr) and [(C12H25)(2)(CH3)(2)N]PbI2 (DLDMPbI) were synthesized, and the structural characterizations were performed on X-ray diffraction and optical measurements. The absorption peaks of these compounds showed higher photon energy than those of conventional layered perovskite compounds with primary alkylammonium ions. This result indicated that novel quantum confinement structures were constructed with the DLDMPbBr and DLDMPbI.

Novel organic-inorganic hybrid compounds, CnN2PbBr4 (n=4,6,8 and 10) and C2N2PbBr4 . DMSO, were prepared by the self-organization of lead bromide and a variety of alkyldiammonium cations. The powder X-ray diffraction patterns of CnN2PbBr4 demonstrated that the compounds form layered perovskite structures and the interlayer spacing are dependent on the length of alkyl chain. The absorption and fluorescence spectra of CnN2PbBr4 and C2N2PbBr4 . DMSO crystalline powder showed an excitonic absorption peak at around 390 nm, which suggests that the formation of two-dimensional inorganic sheets and quantum confinement structure.