Research articles

Sulfonated polymers are promising polyelectrolyte for polymer electrolyte fuel cells (PEFCs) in the next generation. We found that the sulfonated polyelectrolyte can wrap multi-walled carbon nanotubes (MWNTs). After the reduction of Pt salt in the presence of the polyelectrolyte-wrapped MWNTs, Pt-nanoparticles below 5 nm in diameter with a narrow distribution were found to be homogeneously loaded. The composites are composed from the electron conductor, proton conductor and the catalyst metal, which are all necessary for the electrocatalyst for fuel cell and are promising materials for PEFC in the next generation.

In situ small-angle X-ray and neutron scattering (SAXS and SANS) measurements were conducted on an isotropic blend of deuterated polyethylene (97 wt%) and hydrogenated polyethylene (3 wt%) during uniaxial drawing at 125 °C to clarify the formation mechanism of shish-kebab from isotropic film. Figure shows that 2D SANS and SAXS patterns in the various drawing ratio, R_D, conditions. The drawing direction is longitudinal. In R_D=8, the streak-like scattering in the normal direction of drawing became stronger only in the SANS, showing that more hydrogenated polyethylene chains were merged into the shish.

The oxidative polymerization of thiophene derivatives were carried out using palladium (II) acetate as a catalyst in the combination with copper (II) acetate and trifluoroacetic acid under oxygen atmosphere. The poly(3-hexylthiophene) (P3HT) obtained by palladium catalyzed polymerization showed that head-to-head content was richer than authentic one prepared by a conventional oxidant, and that maximum absorption, and luminescence wavelengths of the P3HT are blue-shifted to 338 and 534 nm in ultraviolet and photoluminescence spectra, respectively. The catalytic system was also applied for the polymerization of 3,4-disubstituted thiophene monomers.

The mechanical characteristics of a non-ionic polymer, lipid-based complex fluid that exhibits a thermoinverted phase transition (sol phase at lower temperature than the gel state) were examined by combined rheology, small-angle X-ray, and neutron diffraction studies and Raman spectroscopy. The temperature-driven water solubility and thus conformational changes of amphiphile-tethered polyethylene oxide (PEO) regulates the formation and strength of the hydrogen-bonded network. These studies identify principles useful in the preparation of stimuli-responsive mechanical materials.

Poly(arylene ether ketone)s composed of 1,8-diaroylenenaphthalene moiety, a non-coplanarly accumulated aromatic-rings unit, have been successfully synthesized via nucleophilic aromatic substitution polycondensation of 1,8-bis(4-fluorobenzoyl)-2,7-dimethoxynaphthalene with several arene diols under mild conditions. The polymers show high glass transition temperature (T_g), poor solubility and good film-forming ability by heat casting.

Dendrimers are attractive polymers with a well-defined structure and multivalent terminal groups. We have designed a novel type of peptidomimetic based on dendrimer by modifying the amino acids at the periphery of the dendrimer. The dendritic peptidomimetic containing Pro and Arg was bound to a model protein, amphiphysin II SH3 domain, at a similar level to a model binding peptide, a Pro-rich sequence of dynamin.

Carboxymethyl chitosan(CMCTS), one of the chitosan derivates, is a zwitterion and potentially could be used as a kind of immunomodulator. The aim of this study is to investigate the immunological enhancement effects of CMCTS in vitro and provide an important theoretical evidence for its clinical practice.

The intercalated structures for the high-impact polystyrene (HIPS) nanocomposite materials that were prepared with 5 wt% Cloisite 30B (C30B) (a) and 5 wt% Cloisite 10A (C10A) (b) are shown in the transmission electron microscopy images. Although an intercalated structure is present in the sample (b), some individual platelets can also be observed because the material remains thermally stable when it undergoes melt compounding. The higher thermal stablility of the HIPS/C10A nanocomposite materials in comparision with the HIPS/C30B nanocomposite materials was proved by the mechanical testing and the rhecometer and thermal analysis.

Styrene and methyl methacrylate diblock copolymers were synthesized by sequential living anionic polymerization, and the fractal-like hierarchical micro-/ nano-rough structures of the copolymer surfaces with superhydrophobicity were prepared by using phase separation method. When the ethanol content in the mixed solvents was 60%, the copolymer surfaces with water contact angle (WCA) of 156.7° and low contact angle hysteresis (7.1°) was obtained. The copolymer surfaces had excellent self-cleaning ability.

The giant single crystals of isotactic polypropylene (iPP) were obtained by a specific kinetic path through the mesophase of iPP. The obtained crystallites showed a very high melting temperature immediately near the iPP’s equilibrium melting temperature. The crystallites have bamboo leaf-like or needle-like morphology having several tens μm in length, several μm in width and 88 nm in thickness. The number density of the crystallites in a unit volume was controlled by adjusting the heating rate, resulting in well-isolated single crystals.

Polyurethane networks (PUN) were synthesized by reacting poly(ethylene glycol) and hexamethylene diisocyanate with poloxamer Tetronic 701 or poly(ɛ-caprolactone)s triols. The hydrophilic/hydrophobic ratio was varied by selecting the appropriate amounts of monomers, and its effect on swelling behavior and thermal properties was analyzed. Drug-release studies evidenced that these materials hold promise as implantable drug-delivery devices and antimicrobial coatings.

A series of soluble and autophotosensitive hyperbranched polyimides were successfully prepared. The hyperbranched polymer (HBPI) films showed excellent solubility, low dielectric constant and a minimum birefringence value as low as 0.0026 at 650 nm. In addition, HBPI-1 and 3, exhibited excellent optical properties and good photolithographic properties, may be considered as promising processable high-temperature materials for applications in microelectronic and optical devices.

¹²⁹Xe NMR spectra of ¹²⁹Xe in polyphenyleneoxide, PPO were measured at various temperatures below T_g. From the analysis of ¹²⁹Xe NMR chemical shifts, the mean volume of individual microvoids in PPO, v could be determined. The temperature when value of v becomes same as a Xe atom, was very close to T_g of PPO. Temperature dependence of individual microvoid’s volume was very similar with that of C_H′, which is obtained by dual-mode sorption model from Xe sorption isotherms and is corresponding to the unrelaxed volume of PPO in the glassy state.

Monodisperse polystyrene particles were prepared by enzymatic emulsifier-free emulsion polymerization using a horseradish peroxidase (HRP)/H₂O₂/β-diketone system in water. The resultant polymer particles were stabilized by the β-diketone moieties located at the surface of the particle. Enzymatic emulsifier-free emulsion polymerization might offer a practical method for the preparation of polymer particles under mild enzymatic conditions (that is, room temperature and surfactant-free).

This study demonstrated that synchrotron radiation ultra-small angle X-ray scattering (SR-USAXS) enable us to evaluate the outermost surface and ‘buried’ periodic structure without any pretreatment and sample damage. Surface and ‘buried’ nanostructure were fabricated on poly(lactic acid) film by nanoimprint lithography. The resulting films were characterized by SR-USAXS. The size of surface and ‘buried’ structure were successfully determined by the analysis of scattering pattern.

Schematic model of solvent bound in iPP gel. Free and freezable bound solvent locates between intra- and interspherulites, respectively.

Xe sorption properties of tetramethyl bisphenol A polycarbonate (TMPC)/polystyrene (PS) blends indicated the reduction of microvoids by blending. From the analysis of ¹²⁹Xe NMR chemical shifts of the ¹²⁹Xe in these blends, the mean volume of individual microvoids (v) was calculated. The v values for these blends were smaller than those of predicted by a simple additive rule, as well as the cases of variation of density and Xe sorption properties. This fact indicates that the volume contraction induced by blending for TMPC/PS blends is mainly attributed to contraction volume of individual microvoids.

The hydrogen dissolved in acrylonitrile butadiene rubber due to high-pressure hydrogen exposure was analyzed by solid-state ¹H NMR. On the basis of pressure dependency of chemical shift of free hydrogen and relaxation time of dissolved hydrogen, the hydrogen with two different characters at 4.3 and 4.8 p.p.m. were ensured to be with different mobility. Conversion of the ratio of the two states of hydrogen suggested the transition of hydrogen from the state constrained to rubber chemical structure to free volume during hydrogen elimination process.

Ion-conductive behavior of a novel polymer electrolyte without oxyethylene units, poly(ethylene carbonate) (PEC)-Li salt system, was reported. Salt-concentration dependence revealed that the LiCF₃SO₃ and LiClO₄ electrolytes exhibit typical polyether-like conduction behavior. However, the LiBETI, LiBF₄ and LiTFSI electrolytes were much different, and the conductivity increased and T_g decreased with increasing salt concentration. This behavior of salt-rich PEC electrolytes relates to the ‘polymer-in-salt’ system. Li⁺ transference number of PEC-LiBF₄ (44.4 wt%) electrolyte was measured, and the value was estimated to be ∼0.5 at 100 ^oC.

A sulfonated aromatic block copolymer (SABC), consisting of hydrophobic and hydrophilic blocks, was analyzed by 2D NMR techniques of HSQC, HMBC and HSQC–TOCSY. Because of its complicated chemical structure with five different phenylene rings, 12 types of ¹H signals and 24 types of ¹³C signals were observed in a narrow chemical shift range (7.0–8.0 p.p.m. for ¹H and 118–162 p.p.m. for ¹³C). As a result of these studies, complete ¹H and ¹³C NMR signal assignment of SABC was performed.