Novel thermal curing reaction of oxetane resins with polyfunctional phenols

The thermal curing reaction of polyfunctional oxetanes (oxetane resins) such as tris[4‐(3‐ethyloxetane‐3‐yl)methoxyphenyl]methane (TEOMP) and 1,3,5‐tris(3‐ethyl‐3‐oxetanylmethoxy)benzene with certain polyfunctional phenols was performed in bulk with quaternary onium salts as catalysts. The reaction proceeded smoothly at 180–220 °C and produced insoluble gel products, and the rate of gel production increased with the reaction temperature. The rate of the addition reaction of TEOMP with 3,3′,5,5′‐tetrachlorobisphenol A was also measured by IR spectroscopy, and the rate of reaction was proportional to the product of the oxetane concentration and the catalyst concentration in the film state. Furthermore, the glass‐transition temperatures and 5 and 10 wt % weight‐loss temperatures of the resulting gel products were confirmed with differential scanning calorimetry and thermogravimetric analysis, and the glass‐transition temperatures and 5 wt % weight‐loss temperatures were 127–162 °C and 323–351 °C, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2028–2037, 2005     

Aspects of nucleation and drift processes in a one-dimensional model

We introduce a one-dimensional model involving the nucleation and the drift of many particles. The model originates from interacting kink systems and simulates time evolution in modulated systems. In this model the nucleation rate of a particle depends nonlocally on the density of preexisting particles and the drift of particles is due to a weak and repulsive interaction among them. We first study the statistics of this model in the case that the drift of particles is negligible, and then consider the effects of the drift of particles.     

Recent Advance in Terahertz Wave and Material Basis

The unexplored terahertz (THz) region involves important phenomena of both fundamental and applied natures. Examples include phonon interactions, rotational transitions, and intermolecular dynamics. Frequency tunable high-power THz wave generation has been successfully achieved utilizing lattice resonance of LiNbO₃ and GaP crystals, respectively. Semiconductor devices utilizing the electron tunneling effect have also been developed.     

Stereoselective synthesis of microcarpalide

Microcarpalide is a strong microfilament disrupting agent. The convergent and stereoselective synthesis of microcarpalide was succeeded via Julia olefination and macrolactonization.     

Measurement of MHD combustion-gas temperatures and potassium number densities in the presence of cold boundary layers

The wing-reversal method is useful, with small influence by self-resonant absorption, for the measurement of MHD combustion-gas temperatures in the presence of cold boundary layers. We show how the errors caused by self-absorption in the wing-reversal method are obtained by using correction factors for temperature and potassium atom density in boundary layers, without numerical integration of the radiative transfer equation. The radiative transfer equation and the absorption coefficient of potassium may be simplified when the optical thickness is appreciably smaller than unity. We have used this method on MHD combustion gases. The measured main flow temperature agrees with the thermal equilibrium temperature within 1%, while the measured main flow potassium atom density is about 65% of the equilibrium density.