Gravitational Effects on Mixing and Growth Morphology of an In0.5Ga0.5 System

A mixing experiment of multicomponents melts was performed using a uniform temperature furnace in the Second International Microgravity Laboratories (IML-2) mission. Growth morphologies and Ga concentration profiles were analyzed for the samples with the compositional ratio of 0.5 In–0.5 Ga–1.0 Sb grown under microgravity and on earth. The sample with free surface grown under microgravity was nearly spherical in shape, except some parts with projections. Ga was dispersed homogeneously in the bulk because the mixing was enhanced by Marangoni convection due to the concentration gradient. On the other hand, the sample grown on earth was a double cylindrical shape with different diameters, and Ga concentration decreased from top to bottom, showing clearly the effect of gravity. Many needle crystals were formed in both space and earth samples due to rapid cooling. The average size of the needle crystals grown in space was larger than that of the earth sample.     

Storage Modulus and Surface Morphology of Poly(vinyl alcohol)/Alumina Hybrid Hydrogels

The storage moduli, shear moduli and surface morphologies of poly(vinyl alcohol) (PVA) and alumina hybrid hydrogels were investigated. The storage moduli of hybrid hydrogels with higher alumina contents were found to be 1.5 times higher than those of PVA gels. This increase in modulus might be attributed to the cohesion of alumina to the PVA network.

SEM photograph of Al7 PVA/alumina hybrid hydrogel. The photograph was taken with a magnification of × 220.     

Enzymatic synthesis and characterization of amphiphilic block copolymers of poly(ethylene oxide) and amylose

Amphiphilic A‐B block copolymers, ω‐methoxypoly(ethylene oxide)‐amylose copolymers (MPEO‐amylose), were synthesized by an enzymatic reaction using potato phosphorylase from an MPEO (M_w = 5.0×10³)‐maltopentaosylamine derivative as a primer and α‐D ‐glucose‐1‐phosphate as a substrate. MPEO‐amyloses with various molecular weights of amylose (DP = 26, 36, 73 and 112) were obtained. None of the MPEO‐amyloses (5 mg/ml) precipitate in water containing 10 vol.‐% DMSO even after 24 h. The MPEO‐amyloses effectively form complexes with iodine in water.     

Preparation of Polymer-Supported Chiral 1,2-Diamine as an Efficient Ligand for Asymmetric Hydrogenation Catalyst

An enantiopure 1,2-diamine having two phenolic hydroxy groups was synthesized, and attached to chloromethylated poly(styrene) through a benzyl ether linkage. The polymer-supported Ru precatalysts were prepared from the polymeric chiral 1,2-diamine and RuCl₂/BINAP complex. In the presence of t-BuOK the polymeric catalyst system worked well in asymmetric hydrogenation of aromatic ketones in a mixed solvent of 2-propanol and DMF. The insoluble polymeric catalyst was readily separated from the reaction mixture and reused at least several times without loss of the catalytic activity.