Articles in 2013

Laminated film composite was fabricated by stacking the surface-modified poly(ethylene terephthalate) films using the initiated chemical vapor deposition (iCVD) method, with a ultraviolet (UV)-curable methacrylate-polyhedral oligomeric silsesquioxane (POSS) inorganic polymer interlayer binder to develop an alternative glass material. The 11-layered PET film/POSS composites were consolidated by UV exposure, and it increased modulus and maintained transmittance and haze.

High ordered structure, thermal property and surface wettability of a novel alternated copolymer of vinylidene cyanide and perfluorooctyl ethyl vinyl ether were investigated with wide-angle X-ray diffraction, differential scanning calorimetry, X-ray photoelectron spectroscopy and contact angle measurement. The alternated copolymer showed a smectic liquid crystalline structure and extremely high isotropization temperature of 150 °C, compared with 29.5 °C for the perfluorooctyl ethyl vinyl ether homopolymer. The alternated copolymer also showed large contact angle hysteresis, indicating that surface reorganization of the polar cyano and ether groups occur.

The morphology and the electronic conductive properties of self-assembled monolayers formed by helical oligopeptides suitably functionalized with electro- and photoactive units were investigated by electrochemical, spectroscopic and atomic force microscopy techniques. The versatility of peptide building blocks was also highlighted by the formation of bicomponent self-assembled monolayers exploiting interchain dipole–dipole interactions.

Three novel conjugated copolymers containing coplanar bithiophenevinyl-(2-pyran-4-ylidenemalononitrile) unit linked with different electron-donating moieties by a double bond were synthesized by Heck polycondensation reactions. By introducing a double bond between the donor and acceptor unit within the backbone of polymers instead of a single bond, the conjugated length was enhanced, and consequently broader absorption spectral range and reduced band gap. Hence, the polymer can absorb more light to get higher Jsc and power-conversion efficiency.

Polymeric pseudo-liquid membrane (PPLM) was constructed from poly(dodecyl methacrylate), which showed rubbery state under membrane transport conditions, as a membrane matrix and dibenzo-18-crown-6 or O-allyl-N-(9-anthracenylmethyl)cinchonidinium bromide as a model transporter. Membrane performance was studied adopting KCl or racemic mixture of phenylglycine as a model substrate. The present results suggest that PPLMs were applicable to not only metal ion transport but also optical resolution.

A detailed study of physical vapor deposition (PVD) technique applied to diphenylalanine (FF) peptides is described, following the self-assembly mechanism of deposited peptide nanostructures.Control of their chemical and physical properties have enabled us to develop a controllable deposition technology for fabricating peptide nanostructures. The PVD process of FF consists of elementary stages: first linear-FF (L-FF) molecules adhere to the substrate forming an amorphous layer, which grows into nanoclusters. Second, either PNT of L-FF or peptide nano fiber of cyclo-FF are formed, depending on the PVD environment.

Complex polymeric hollow spheres were made easy. We reported a facile one-pot solvothermal synthesis of anisotropic polyazomethine particles using the in-situ formed Pickering emulsion as templates. Taking advantage of the dynamic nature of imine bonding and the inhomogeneous nature of the particles, these anisotropic particles can further hollow into and result in complex anisotropic yolk-shell and anisotropic hollow spheres, which were heretofore rarely reported in polymeric systems.

We found that the quenched poly(vinylidene fluoride) (PVDF) film in ice-water became transparent by cold-drawing, whereas PVDF that was slowly cooled on a hot plate became opaque. The transmittance of the quenched PVDF measured by ultraviolet–visible spectroscopy increased by up to 30% in the lower wavelength range (200–600 nm), which increased the transparency. The decrease in the density difference between the lamellar crystal and the lamellar amorphous phases might increase the transmittance of the quenched PVDF in the lower wavelength range.

This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.

The morphology of PLLA/PBA crystalline/crystalline system reveals abundant morphologies in different crystallization condition. Neat PLLA and PBA usually show Maltese-cross spherulites. However, banded spherulites and branched structures of blends formed in high-temperature region in this work. In addition, fragments morphology is discovered in low-temperature region. These different morphologies are related to the changes of crystallization environment caused by crystalline/crystalline blending.

Mesoporous monolith of poly(vinyl alcohol) (PVA) is successfully prepared by thermally impacted non-solvent induced phase separation without any templates. The pore and skeleton sizes can be controlled by changing the cooling temperature as well as the concentration and molecular weight of PVA. The nitrogen adsorption–desorption isotherms show that the PVA monolith has large surface area and uniform mesopore structure. The crosslinking using glutaraldehyde (GA) as crosslinking agent produces the water-insoluble monolith. By changing the concentration of GA, the crosslinked monolith with different swelling ratios toward water is obtained.

Zinc diacrylate (ZDA) gave the polymer as shown in the scheme by heating in the solid state. When additives like diphenyl disulfide (DPDS), thiophenol (TP) and dicumyl peroxide (DCP) were mixed in 1/60 molar ratio to ZDA, qualitative order of the polymerization rate was obtained to be ZDA < ZDA-DPDS(or TP) << ZDA-DPDS(or TP)-DCP < ZDA-DCP. Namely, mixing these additives to ZDA accelerated the solid-state polymerization.

Diblock functional poly(ɛ-caprolactone)s (PαN₃CL-g-BioM)-b-PCLs grafted with bioactive molecules were performed by Huisgen’s 1,3-dipolar cycloaddition. These amphiphilic copolymers can self-assemble into micelles in the aqueous medium with critical micelle concentration (CMC) in the range 4.6–20 mg l⁻¹, and the average micelle size ranged from 105 to 162 nm. In vitro cell viability assays showed that (PαN₃CL-g-BioM)-b-PCL has low cytotoxicity.

The recent progress of research on polymer reactions utilizing dynamic covalent exchanges of alkoxyamine units—adducts of styryl and stable nitroxide radicals—is reviewed. Various types of macromolecular design, polymer reactions based on dynamic covalent exchanges of alkoxyamine units and their related research are described. Various examples of polymer reactions of main-chain-type, side-chain-type, crosslinked and star-shaped poly(alkoxyamine)s are systematically shown. The progress of the polymer reactions can be confirmed by diverse characterization techniques, such as spectroscopic, chromatographic, microscopic and scattering methods.

Synthetic spider fibers have particular structural and mechanical features that can be improved through extrusion treatments. The surface irregularity, elasticity and strength of fibers are likely to be dependent on their molecular organization and an alcohol bath appears to initiate the transition of random coil structures to β-sheets, resulting in smoother, stronger and more elastic fibers. Atomic force microscopy/force spectroscopy complemented by scanning electron microscopy was able to qualitatively describe synthetic fibers and quantify their roughness and mechanical properties, representing a significant step toward spider silk characterization, and for its application as a biomaterial.

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.

The existence of intramolecular CH/π interaction of four soluble polyfluorenes (PFs) and molecular di-n-octylfluorene in chloroform-d₁ at 20 °C was first revealed by cross-peaks of the ring with several protons of alkyl groups in ¹H–¹H NOESY NMR and marked upfield shift of several alkyl proton signals in ¹H-NMR spectra. Only the PF bearing β-branched chiral groups at 9,9-positions among three chiral PFs in chloroform at 20 °C showed intense circular dichroism bands in the π−π* region because of the intramolecular CH/π interaction. Conflex7 and Gaussian 03 MP2 calculation results supported this idea.

Aib/Ala-containing peptides, lacking any charge or polar group, dissolve in water by forming spherical aggregates with diameters up to 100 nm. These self-assembled nanostructures are able to incorporate molecules of relevant size, such as decorated Au nanoparticles. Such systems may widen the number of applications currently accessible to self-assembled aggregates in the fields of biomedicine and materials science.

Donor–acceptor-type alternate polymers composed of dithienometallole (metal=Si or Ge) and pyridinocalcogenadiazole (chalcogen=S or Se) units were obtained as black solids, which showed highly red-shifted broad bands centered at 732–745 nm in chlorobenzene. Photovoltaic properties of the polymers were examined as blend films with PC₇₀BM and the maximum power conversion efficiency of 3.46% was obtained.

Polyrotaxane (PR)-protected glycine conjugates with different levels of degrees of substitutions (DS) were successfully prepared by varying reaction temperature, reaction times and stoicheometric ratios of AA to −OH in PR. Variation of the stoicheometric ratios enabled the widest control of DS values. Z-protecting groups of pendant glycine were removable only by trifluoroacetic acid/thioanisole system.