Interpenetrating Polymer Networks with Spatially Graded Morphology Controllable by UV-Radiation Curing

Interpenetrating Polymer Networks (IPNs) composed of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were synthesized from a precursor mixture by using dissimilar photo-cross-link reactions. When the reation yields exceeded a certain threshold, the mixture was quenched from one-phase region into two-phase region, leading to phase separation. Upon irradiation with strong UV-light, an intensity gradient was formed along the propagating direction of the exciting light, generating a gradient of quench depth via the spatial inhomogeneity of the cross-link reactions. As a consequence, a gradient of the characteristic length scales was continuously generated from the top to the bottom of the mixture. The resulting three-dimensional (3-D) morphology was in-situ observed at different depths of the mixture by using a laser-scanning confocal microscope (LSCM). From this 3-D observation, it was found that phase separation was accelerated at the bottom of the mixture and proceeded in an autocatalytic fashion. The mechanism for the formation of the graded morphology was discussed in conjunction with the kinetics of the autocatalytic phase separation.     

A novel promoter, heteropoly acid, mediated chemo- and stereoselective sulfoxide glycosidation reactions

The chemo- and stereoselective glycosidations of sulfinylglycosides and alcohols using a heteropoly acid, H₃PW₁₂O₄₀, as a new promoter have been developed.     

Intense THz-radiation from semiconductors under magnetic field irradiated with femtosecond laser pulses

The THz-radiation power from InAs reaches sub-mW level in a 1.7-T magnetic field irradiated with femtosecond laser pulses of 1.5-W average power. The THz-radiation power is related almost quadratically both to the magnetic field and to the excitation laser power. Furthermore, the THz-radiation spectrum is found to be controlled by the excitation pulsewidth, chirp direction of the excitation pulse, and the magnetic field.     

Conjugated ketonic fatty acids from Pleurocybella porrigens

Three novel conjugated long-chain fatty acids (1-3) were obtained from aqueous methanol extracts of Pleurocybella porrigens together with nine known constituents including (8E,10E)-7,12-dioxo-8,10-octadecadienoic acid (ostopanic acid) (4). The structures of the new fatty acids were characterized as (14RS)-(10E,12E)-14-hydroxy-9-oxo-10,12-octadecadienoic acid (1), (12RS)-(8E,10E)-12-hydroxy-7-oxo-8,10-octadecadienoic acid (2), and (10E,12E)-9,14-dioxo-10,12-octadecadienoic acid (3) by spectroscopic methods.     

Photo-Deformation of Syndiotactic Polystyrene Gels

We report a usual and novel phenomenon that an excitation light beam of a spectrofluorometer produced a black mark in gels of syndiotactic polystyrene (SPS). This mark whose shape is identical with that of an excitation light beam was found to appear in SPS/chloroform gel just after only irradiation at 260 nm for 5 to 10 min. The heating of the gel with the mark at 80°C diminished the mark and recovered uniformly the gel to be as it had been before irradiation. We discuss what the black mark is and why it is produced by light irradiation.     

Controlled synthesis of thermoresponsive polymers derived from L-proline via RAFT polymerization

Well-defined polymers derived from L-proline are synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization and the amino acid-based polymers exhibit thermosensitive phase separation at lower critical solution temperatures (LCST = 15-45 degrees C) in aqueous medium.     

Photo-initiated bromination of octakis(1,1,2-trimethylpropyl)octasila- cubane with tetrabromomethane

Bromination reactions of octasilacubane via radical intermediates are demonstrated. In the absence of oxygen, UV-light irradiation of octakis(1,1,2-trimethylpropyl)octasilacubane (1) with tetrabromomethane in benzene resulted in the formation of only exo,exo-4,8-dibromoctakis(1,1,2-trimethylpropyl)tetracyclo[3.3.0.0^2,7.0^3,6]octasilane(2). However, in the presence of oxygen, the reaction of 1 with tetrabromomethane took place without irradiation, producing 2 and a novel type of the monooxidation product, dibromooxahomosecocubane (3). For the formation of these products, an electron-transfer mechanism involving successive cleavage of the Si–Si bonds, followed by skeletal rearrangement is proposed.     

Diastereoselective addition of alcohol to diastereotopic silylenes

The successful example of diastereoselective addition of alcohol to diastereotopic silylenes is reported.     

Improved apparatus for solid-liquid multi-stage counter-current extraction

An improved apparatus for solid-liquid multi-stage counter-current extraction (SLME) was developed. The apparatus has a set of 24 extraction vessels. Each extraction vessel unit is composed of a piston-cylinder in which the solid phase is placed, and a cup-cylinder in which the liquid phase is set. Of the 24 extraction vessels, 20 were used for the separation stage, and the other 4 were used for the back-extraction stage. (+/-)-Troger's base was selected as a racemic model compound for the continuous enantioseparation by the apparatus, and a cellulose derivative was used as the chiral separator. After 50 cycles of the operation (in 9 h), 0.1 g of (-)-enantiomer (85% in purity) was recovered from the solid phase by back-extraction with ethanol, whereas 1.1 g of (+)-isomer (75% in purity) was collected from the liquid phase (ethanol).