Effect of poly(butylene succinate) crystals on spherulitic growth of poly(ethylene oxide) in binary blends of the two substances

The effects of the lamellar growth direction, extinction rings, and spherulitic boundaries of poly(butylene succinate) (PBSU) on the spherulitic growth of poly(ethylene oxide) (PEO) were investigated in miscible blends of the two crystalline polymers. In the crystallization process from a homogeneous melt, PBSU first developed volume‐filling spherulites, and then PEO spherulites nucleated and grew inside the PBSU spherulites. The lamellar growth direction of PEO was identical with that of PBSU even when the PBSU content was about 5 wt %. PEO, which intrinsically does not exhibit banded spherulites, showed apparent extinction rings inside the banded spherulites of PBSU. The growth rate of a PEO spherulite, G_PEO, was influenced not only by the blend composition and the crystallization temperature of PEO, but also by the growth direction with respect to PBSU lamellae, the boundaries of PBSU spherulites, and the crystallization temperature of PBSU, T_PBSU. The value of G_PEO first increased with decreasing T_PBSU when a PEO spherulite grew inside a single PBSU spherulite. Then, G_PEO decreased when T_PBSU was further decreased and a PEO spherulite grew through many tiny PBSU spherulites. This behavior was discussed based on the aforementioned factors affecting G_PEO. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 539–547, 2009     

Spin resonance spectroscopy of grown-in defects in Ga(In)NP alloys

We employ the optically detected magnetic resonance (ODMR) technique to study and identify important grown-in defects in Ga(In)NP grown by molecular-beam epitaxy (MBE). Several types of defects were revealed from ODMR studies. The dominant defects were found to be related to Ga interstitials, evident form their characteristic hyperfine interaction arising from the spin interaction between the electron and the Ga nucleus. Some other as yet unidentified intrinsic defects were also found to be commonly present in the alloys. The effects of growth conditions (ion bombardment, N₂ gas flow, etc.) and post-growth rapid thermal annealing on the formation of these defects were studied in detail, shedding light on the formation mechanism of defects.     

Synthesis and reactions of benzopentathiepin having hydroxyl group

The synthesis of benzopentathiepin having a hydroxyl group at the neighboring position of polysulfur ring was performed by demethylation of 6-ethyl-9-methoxybenzopentathiepin with hydrogenbromide. Benzotrithiole having hydroxyl group was not isolated at all. The hydroxyl group was also alkylated with alkyl iodide in the presence of weak base.     

Hydrogen bond network-stabilisation of blue phases by addition of a chiral N-(10-hydroxydecyl)succinimide derivative and alkane diols

Blue phases (BPs) obtained by doping a commercially available liquid crystalline compound (4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA)) with (2R,3R)-2,3-bis(4-octyloxyphenylbenzoyloxy)-N-(hydroxydecyl)succinimide (1) were highly stabilised by the addition of a small amount of alkane diols. Especially, addition of only 0.5 mol% of octane-1,8-diol increased the BP–Iso transition temperature by 10 K and widened the BP temperature range up to 35 K. A model stabilisation mechanism based on the construction of a hydrogen bond network in each disclination zone in BPs was proposed.     

Preparation of Enzymatically Recyclable Hydrogels Through the Formation of Inclusion Complexes of Amylose in a Vine‐Twining Polymerization

In this paper, we describe the preparation of hydrogels through the formation of an inclusion complex of amylose in a vine‐twining polymerization. This is achieved by the phosphorylase‐catalyzed polymerization of α‐D ‐glucose 1‐phosphate from maltoheptaose primer, in the presence of a water‐soluble copolymer having hydrophobic graft‐chains (poly(acrylic acid sodium salt‐graft‐δ‐valerolactone)). The mixture turns into a gel during the polymerization process. Evaluation of the hydrogels is conducted by shear‐viscosity measurements of the products. For the hydrogels with relatively high viscosities, fast relaxation modes of the cooperative diffusions are observed by scanning microscopic light scattering measurements, which indicate the nanometer‐size network structures of the hydrogels. In addition, we found that the enzymatic disruption and reproduction of the hydrogels are achieved by the combination of the amylase‐catalyzed hydrolysis of the amylose component and the formation of amylose by the phosphorylase‐catalyzed polymerization.     

Three-dimensional electronic structure in highly doped NaxCoO2 studied by angle-resolved photoemission spectroscopy

We have investigated three-dimensional electronic structure for Na_xCoO₂ (x=0.77 and 0.65) by high-resolution angle-resolved photoemission spectroscopy to study the origin of antiferromagnetic (AF) transition of highly doped Na_xCoO₂(x>0.75). The a_1g large hole-like Fermi surface (FS) in x=0.77 shows distinct three-dimensionality along the k_z direction, and a three-dimensional small electron pocket appears around Γ point, indicating strong inter-layer electronic correlation. On the other hand, x=0.65 sample does not show three-dimensional behavior. This result indicates that transition of FS as a function of band filling is closely related to the occurrence of the magnetic transition in highly doped Na_xCoO₂.