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Isolated molecules of cyclic polymers were directly observed by atomic force microscopy. Interdiffusion of cyclic polystyrene/cyclic deuterated polystyrene bilayer films were investigated as functions of temperature and molecular weight by dynamic secondary ion mass spectroscopy.
Ni(0)-catalyzed coupling polymerizations of 3,6-di(4-chlorophenyl)-3,6-dihydrophthalic acid diethyl ester 1 were accompanied by isomerization of the 1,4-cyclohexadiene moiety into a 3,5-cyclohexadiene group, yielding a conjugated polymer. The structure of this conjugated polymer was the same as that of the conjugated polymer from 3,6-di(4-chlorophenyl)-1,2-dihydrophthalic acid diethyl ester 2. The conjugated polymer exhibited a λ max at 430 nm in the absorption spectrum, and could be applied as a photo-sensitizer of a solar cell. The incident monochromatic photon (450 nm)-to-current conversion efficiencies of photocurrent from an ITO/TiO2 electrode modified with the conjugated polymer was 6.1% in the I3--3I- electrolyte wet system.
The nanoscale structures of graft-type PEMs, prepared by radiation-induced graft polymerization of styrene onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films followed by sulfonation, were investigated using a small-angle neutron scattering (SANS) technique. The SANS profiles of the grafted films showed shoulder peaks at a d-spacing of ∼30 nm, which were attributed to the polystyrene grafts introduced into the amorphous phases between the ETFE lamellar crystals. In the ETFE PEMs, this d-spacing increased to 34 nm because the graft regions were enlarged by the volume of the attached sulfonic acid groups.
The particle scattering function (structure factor) P(q) of a two-dimensional flexible macromolecule (2D-FM), such as thin graphite oxide and graphene oxide, was calculated. The geometrical model used for shrinking the 2D-FM particle was the developable double corrugation surface (Miura folding) of a disk. This model described a three-dimensionally foldable and re-extendable shape and spontaneously exhibited self-avoiding condition inside a single particle. The obtained P(q) varied greatly according to the shape of the particle, which can change from a flat extended state to a three-dimensionally isotropic and dense shrunken state.
Individual holes and fractal-like structures have been prepared using solid films of conjugated polymers via solvent vapor annealing. A high environmental humidity is crucial for the formation of the holes and the fractal-like structures. But, the formation of the holes and the fractal-like structures is not dependent on the polarity of the surfaces of the substrates. The fractal-like structures can be preserved upon conversion of the thermal cleavable polythiophene films to the insoluble polythiophene films.
In this manuscript, we report the doped thin films consisting of a nanofiber network of a conducting polymer, poly(3-hexylthiophene), were fabricated, and optical transmittance and electrical conductivity measurements were carried out. The superior properties of the nanofiber films in the transparency and conductivity were ascribed to the effective conducting pathways, a large void fraction, and a high dopant concentration due to the large surface area.
Carrageenan-based magnetic composites were prepared via in situ synthesis of iron oxides in a gelatinous network of the polysaccharide. Magnetic properties and morphology were characterized by SQUID magnetometry, X-ray diffractometry and electron miscroscopy. By operation of 3–4 cycles of the standard synthesis route, a carrageenan composite imparting a high value of saturation magnetization (∼25 emu (g sample)−1) was easily realized while the superparamagnetic property at room temperature was maintained. Insight was provided into the evolution mechanism in oxidation state and dimensional distribution of the cyclically loaded iron oxide nanoparticles.
SWNTs have been successfully grafted with polyisoprene (PIp) via anionic polymerization initiated by carbanion-bearing SWNTs. Carbanions were fixed on SWNTs by treating SWNTs with sec-butyllithium, and then the PIp chains grew from these carbanion. The polymer chains were covalently attached to the SWNTs, which leads to the coating of carbon nanotubes and finally to the destruction of the nanotube bundles.
A versatile post-modification method for polyimides using CT complex formation between electron-deficient naphthalenediimide units in the polyimide and electron-rich dihydroxynaphthalene was developed. The film preparation by CT complex formation reported in this paper is an attractive method for functionalization of polyimides because many donor molecules and polyimides can be used. The supramolecular methodology shown here is quite simple, but is an innovative method for polyimide modification.
PHBV/gelatin/laminarin (PHGL) biocomposite nanofibers composed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), gelatin and laminarin were prepared by electrospinning process. The control of mixing ratio between gelatin and laminarin is the most important factor for the improvement of cytocompatibility of synthetic biodegradable polymer, PHBV. PHGL biocomposite nanofibrous scaffolds proved to be promising biomaterials suitable for tissue engineering.
Toward parallel enzymatic synthesis of biologically and pharmaceutically important glycopeptides, we investigated the feasibility of aminooxy-functionalized G7 PAMAM dendrimer derivative in the enzyme-assisted synthesis of glycopeptides having oligosaccharide side chains. The G7 PAMAM dendrimer was proved to become a nice supporting material that exhibited 99% recovery in a simple centrifugal ultrafiltration (UF) procedure in comparison with the hollow-fiber UF module (86%) used in the high-performance liquid chromatography-based automated glycan synthesizer. An optimization of the protocol was performed for the synthesis of glycopeptides bearing di-, tri- and tetrasaccharide branches.
Photopolymerization of thin layers of a 75/25 (w/w) Bis-GMA/TEGDMA mixture exposed to a 465-nm monochromatic light radiation was first investigated. The final methacrylate conversion was measured by FTIR spectroscopy for different light intensities I0. Then, the variation of the light flux intensity φ inside thick samples of the previous mixture containing mineral nanofillers (Al2O3 or ZrO2) was calculated by means of a numerical model by taking into account the light scattering induced by the fillers. The obtained results permit the determination of the conversion profiles inside the loaded material and the maximal thickness that can be photopolymerized without consequent alteration of the polymerization yield and of the mechanical properties.
Polydimethylsiloxane (PDMS) films were doped with 1% perfluoroether to lower the surface energy. Although the surface energy was lowered, the peel force did not decrease. It was found that peel force was linearly related to adhesive energy of films, and adhesive energy was inversely related to Young’s modulus. Films with low Young’s moduli evened out against surfaces easily and made good contact, which increased the adhesive forces, making the release hard. Comparatively, films with higher Young’s moduli had low peel force.
