Note in 2014

For the synthesis of a ladder polyamide, 4,6-diaminoisophthalic acid-type monomers were synthesized and their polymerization was studied. Although the polymerization of the A₂- and B₂-type monomers with a base afforded small molecular weight-products, the polymerization of the AB-type monomer gave higher molecular weight-products. Analysis of the products by means of matrix-assisted laser desorption ionization time-of-flight mass spectrometry revealed that they were composed of polymers and oligomers with linear and cyclic structure.

The alternating copolymers containing planar chiral 4,12-disubstituted[2.2]paracyclophane and quaterthiophene units in the main chain were prepared. The obtained optically active polymers exhibited mirror image Cotton effect, and split in the CD sign that was predicted by the exciton chirality method. A mirror-image CPL response in the polymer solution was also observed with a relatively large g_lum value on the order of 10^–4, suggesting that the polymer forms optically active higher-ordered structures such as zigzag and/or helical structures in the excited state.

It is widely accepted that native xanthan forms a double helical structure and that it loses this structure upon heating (denaturation) and recovers the double helical structure upon cooling its solution (renaturation). The structure of renatured xanthan depends on the concentration of both xanthan and added salt, and temperature. Branched-rods and hairpin-shaped structures were observed by AFM depending on the conditions of denaturation and renaturation. The structural change observed by atomic force microscopy well agrees with the models proposed in our previous study.

The long-term thermal stability of the attenuation of graded-index plastic optical fibers is strongly dependent on whether the glass transition temperature (T_g) of the cladding layer is higher than the environmental temperature. When fibers are exposed to temperatures higher than both the core and cladding T_g values, the core-cladding boundary fluctuates spatially and scatters light. However, our study indicates that the core is not necessarily required to be in a glassy state to maintain a flat, smooth interface as long as the cladding is in a glassy state.

The alternating copolymer containing p-phenylene-ethynylene, 1,2-disubstituted o-carborane and 9,12-disubstituted o-carborane units in the main chain was prepared. Through the Sonogashira–Hagihara coupling, the desired polymer was successfully obtained. The photoluminescence analysis and density functional theory calculation indicated that the copolymer exhibited aggregation-induced emission property by the intramolecular charge transfer from the p-phenylene-ethynylene moiety to the C1–C2 bond of the o-carborane cluster. Thermogravimetric analysis revealed that thermally stable B–C bond enhanced the ceramic yield of the copolymer.

Recovery-after-crosslink behavior observed for PEA-A/PEA blends. For PEA in the matrix with molecular weight smaller than the entanglement molecular weight Me, the recovery was observed, whereas the shrinkage continues upon irradiation for PEA with larger molecular weight.

Suppression of protein adsorption on polymeric interfaces is one of the significant challenges in developing novel biomedical polymers. In this study, the computational design of an antifouling polymer repeat unit is conducted based on a simple approach, whereby the intermolecular affinities between a probe molecule and a polymer repeat unit are evaluated to generate free energy profiles using molecular dynamics simulations. The simplified method affords convenient and theoretical screening of highly antifouling polymer repeat units.

The assembly of molecular components into regular structures is a key ambition of nanoscience and nanotechnology. In this study, we constructed regular assemblies composed of filamentous M13 phages and gold nanoparticles (GNPs). Mixed solutions of gold-binding peptide-displaying phages at the termini (A3 phages) and GNPs behaved as viscous solutions, and GNPs in the solutions were self-assembled into regularly assembled structures. Then, hydrogels composed of A3 phages and GNPs were successfully constructed by chemical crosslinking of phages. In the hydrogels, A3 phages showed liquid-crystalline properties, suggesting high orientation of phages.

Dithienogermole-dithienylbenzothiadiazole alternating polymers with high molecular weights were synthesized. Optical properties of the polymers were investigated with respect to UV-Vis absorption spectroscopy, indicating that the polymer electronic states are highly dependent on the molecular weight, and the nature and position of substituents on the dithienylbenzothiadiazole units. Photovoltaic properties of the polymers in bulk heterojunction-type polymer solar cells were also examined as blend films with PC₇₀BM, affording the power conversion efficiencies of 1.04-3.83%.

We developed a very quick and convenient preparative method for an injectable polymer (IP) formulation to overcome solubility problems of IPs. We investigated the effects of various additives on the dispersion time and gelation behavior for triblock polymers composed of poly(ɛ-caprolactone-co-glycolic acid) (PCGA) and PEG, and found that the addition of PEG with appropriate molecular weight was the best for quick preparation of IP suspension exhibiting temperature-responsive sol–gel transition. This method should be very convenient for usage at clinical scene.

Dispersion of C₆₀/silica nano-composite, prepared by inclusion of C₆₀ into grafted polymer chains on silica, in organic solvent and poly(methyl methacrylate) (PMMA) matrix was investigated. The polymer-grafted SiO₂ particles were prepared by grafting of poly(methyl methacrylate-co-2-naphthyl methacrylate) onto colloidal silica of 9.1 nm in diameter. Inclusion of C₆₀ into the grafted polymer chains was significantly dependent on molecular weight of the polymer and independent on amounts of grafted polymer. The C₆₀/SiO₂-PMMA hybrid film, composed of 0.21% C₆₀ and 10% SiO₂, showed high transparency in visible light region.

We obtained a flexible nano-alloy with a continuous soft, lacy SEB matrix after blending a high-styrene-content styrene-b-styrene-co-butadiene-b-styrene triblock copolymer (S-SEB-S) with a modified poly(2,6-dimethyl-l,4-phenylene ether) (PPE). The simultaneous stress and birefringence measurements revealed that the orientation of the glassy domain is suppressed, and only the soft SEB segments are oriented from the lower strain region in the nano-alloy when compared with those in the S-SEB-S material. Consequently, the S-SEB-S/PPE nano-alloy is flexible despite its blending of the high-styrene-content S-SEB-S with a high-strength PPE.