Living anionic polymerization of ethylphenylketene: A novel approach to well‐defined polyester synthesis

A living polymerization of ethylphenylketene (EPK) was accomplished. When polymerization of EPK was carried out with butyllithium as an initiator in tetrahydrofuran (THF) at −20 °C, EPK was completely consumed within 5 min, and the corresponding polyester with narrow molecular weight distribution (M_w /M_n ∼ 1.1) was obtained almost quantitatively. Kinetic study of the polymerization at −78 °C revealed that conversion of EPK agreed with the first‐order kinetic equation, and that M_n of the polymer increased in virtually direct proportion to the conversion. Along with these results, successful results in postpolymerization at −20 °C strongly supported living mechanism of the present polymerization. Further, lithium alkoxides having a methoxy group, styryl moiety, and nitroxyl radical, also successfully initiated polymerization of EPK to afford the corresponding polymers having functional initiating ends. In the polymerization with varying feed ratio [EPK]₀/[initiator]₀, the linear relationship between the feed ratio and M_n of the obtained polymer was observed, while maintaining narrow M_w /M_n. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1073–1082, 2000     

Nano-crater formation on a Si(1 1 1)-(7 × 7) surface by slow highly charged ion-impact

Using scanning tunneling microscopy (STM) and time of flight secondary ion mass spectrometry (TOF/SIMS), we observed radiation effects on a Si(1 1 1)-(7 × 7) surface in the collision of a single highly charged ion (HCI) with a charge state q up to q = 50. The STM observation with atomic resolution revealed that a nanometer sized crater-like structure was created by a single HCI impact, where the size increased rapidly with q. The secondary ion yields also increased with q in which multiply charged Si ions (Siⁿ⁺) were clearly observed in higher q HCI-collisions. The sputtering mechanism is briefly discussed, based on the so-called Coulomb explosion model.     

A novel redox system consisting of π-conjugated polymers and transition metals

Coordination of π-conjugated polymers to transition metals constructs a novel redox system due to interchangeable various oxidation states of the polymers, which permits transition metals to interact with each other through a π-conjugate chain. The redox characteristics were found to depend on the electronic interaction with metals and the doping. A combination of copper(II) or iron(III) chloride and polyanilines afforded the complex catalysts with the higher oxidation capability for dehydrogenative oxidation. A catalytic system was also realized in the transition-metal-induced oxidation reaction, in which π-conjugated polymers serve as redox-active ligands participating in the reversible redox cycle. The Wacker oxidation of terminal olefins proceeded catalytically in the presence of a catalytic amount of polyaniline or polypyrrole derivative under oxygen.     

Novel Asymmetric and Stereospecific Aziridination of Alkenes with a Chiral Nitridomanganese Complex

The addition of pyridine N -oxide is necessary to obtain high enantioselectivities in the asymmetric aziridination of styrene derivatives through transfer of a nitrogen atom from chiral, toluenesulfonic anhydride activated nitridomanganese complex 1 [Eq. (a)]. Remarkably, high stereospecificity was observed in all the aziridinations of trans- and cis-1,2-disubstituted alkenes. R¹=H, Me, nPr, iPr; R²=H, Me; Ts=p-toluenesulfonyl.     

A finite element analysis of mach reflection by using the Boussinesq equation

The numerical analysis of ‘Mach reflection’, which is the reflection of an obliquely incident solitary wave by a vertical wall, is presented. For the mathematical model of the analysis, the two-dimensional Boussinesq equation is used. In order to solve the equation in space, the finite element method based on the linear triangular element and the conventional Galerkin method is applied. The combination of explicit and semi-implicit schemes is employed for the time integration. Moreover, one of the treatments for the open boundary condition, in which the analytical solution of the linearized Boussinesq equation in the outside domain is linked to the discrete values of velocity and water elevation in the inside domain, is applied for the modeling of the Mach reflection problem. © 1998 John Wiley & Sons, Ltd.