Synthesis and photoproperties of Eu(III)‐bearing star polymers as luminescent materials

Water‐soluble luminescent material was developed by introducing europium (Eu(III)) ions into the core of a star polymer. Living radical polymerization was used to obtain the star polymer. The strategy to introduce Eu(III) ions into the star polymer was studied using poly(methyl methacrylate) as an arm. The best Eu(III) ion introduction was obtained by simultaneous introduction, resulting in about 30 µmol/g‐polymer, which needed only one step for synthesis. The utilization of a hydrophilic polymer such as poly(ethylene oxide) (PEO) as an arm produced a water‐soluble star polymer. The Eu(III)‐bearing PEO star polymer obtained in this study was water soluble and showed fluorescence. In addition, it was stable in water after 1 month. The Eu(III)‐bearing star polymer exhibited luminescent properties under UV light irradiation with relatively high quantum yields of 60% in organic solution and 19% in aqueous solution. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2527–2535     

Time evolution of electron wave-packets in modulated superlattices and at their boundaries

Time evolution of an electron wave-packet moving perpendicular to a superlattice surface is calculated by numerically solving the Schrödinger differential equation. Reflections and penetrations of the wave-packets at the superlattice surface are shown. Low transmission efficiency is observed when the potential discontinuity between two component semiconductors of the superlattice is large, even though the electron impinging energy is in the allowed mini-band of the superlattice. An “anti-reflection coating” which removes this reflection is discussed. The effect of layer-thickness fluctuation on the electron scattering is also simulated by this method. It is found that a fluctuation model of no correlation with neighboring layers produce a scattering rate which strongly depends on the random number sequence used to generate the fluctuation.     

Structure of amauromine,a new alkaloid with vasodilating activity produced by amauroascus sp.

Structure of amauromine (1a), a novel alkaloid with potent vasodilating activity has been established by chemical and spectroscopic evidences.     

On the thickening of lamellar crystals during isothermal crystallization

Summary Two theories on the mechanism of the thickening of chain-folding lamellae occurring during isothermal crystallization are conflicting. One attributes the thickening to an annealing process by which isothermal crystallization should be accompanied. An alternative explanation proposed by the author in the preceding paper, was that the effect should be due to molecular fractionation during crystallization. In order to clarify which of the two conflicting theories is preferable, x-ray long spacings were measured for carefully fractionated polyethylene samples crystallized isothermally and quenched after varying time intervals. In contrast with the previous observation made by Hoffman and Weeks at the crystallization temperature, much less thickening was observed for these samples as compared with the unfractionated polymer (Marlex-50). The effect of crystallization temperature on the thickening behaviour was also examined. Again in favour of the fractionation theory the total amount of the thickening observed decreased remarkably with the decreasing temperature. Further, according to the above two theories the distribution of the fold lengths in the crystals formed was calculated as a function of time for the crystallization of the Marlex-50 polymer. Comparing the results of the calculations with experimental data obtained so far, it has been pointed out that the experimental results afford an evidence in favour of the fractionation theory. A possible effect of an amorphous surface layer on the individual lamella on the observed long spacing increase is also discussed briefly.

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Zusammenfassung Zwei Theorien über den Mechanismus der Dickenzunahme von Faltungslamellen w?hrend der isothermen Kristallisation stehen miteinander in Widerspruch. Die eine schreibt das Dicken-Wachstum dem Temperungsproze? zu, durch den die isotherme Kristallisation begleitet sein sollte. Die andere Erkl?rung, die von den Autoren dieser vorliegenden Arbeit vorgeschlagen wurde, war die, da? Effekte einer molekularen Fraktionierung durch die Kristallisation hinzukommen. Um den Widerspruch zwischen den beiden Theorien zu erkl?ren und zu sehen, welche davon vorzuziehen ist, wurden Weitwinkel-Interferenzen für sorgf?ltig fraktionierte Poly?thylenproben gemessen, die isotherm kristallisiert und nach verschiedenen Zeiten abgeschreckt wurden. Im Gegensatz zu den vorangehenden Beobachtungen durch Hoffman und Weeks bei der Kristallisationstemperatur wurde ein viel geringeres Dicken-Wachstum für diese Proben beobachtet, verglichen mit dem unfraktionierter Proben (Marlex-50). Der Effekt der Kristallisationstemperatur auf das Dicken-Wachstumsverhalten wurde ebenfalls geprüft. Wieder nahm zugunsten der Fraktionierungstheorie der Totalbetrag des beobachteten Dicken-Wachstums betr?chtlich mit abnehmender Temperatur ab. Weiterhin wurde entsprechend den zwei oben angeführten Theorien die Verteilung der Faltungsl?ngen in den gebildeten Kristallen als Funktion der Zeit für die Kristallisation von Marlex-50-Polymeren berechnet. Vergleiche der Ergebnisse der Berechnungen mit den bisher erhaltenen experimentellen Daten zeigen, da? die experimentellen Ergebnisse eine Deutung mit Hilfe der Fraktionierungstheorie begünstigen. Ein m?glicher Effekt einer amorphen Oberfl?chenschicht auf den individuellen Lamellen in dem beobachteten Langperioden-Zuwachs wird ebenfalls kurz diskutiert.

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The major part of this work was done during the author's stay in H. H. Wills Physics Laboratory, University of Bristol, England, and was read at the Annual Meeting of High Polymer Soc. Japan. May, 1965, Tokyo.

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Thanks are due to Dr. A. Keller, University of Bristol, for numerous helpful discussions.     

Kristallisation w?hrend der Polymerisation speziell bei synthetischen Polypeptiden

Ohne Zusammenfassung     

Wachstumsmechanismus der Kristalle von Glyein-L -Alanin-Copolymeren w?hrend der Polymerisation

Ohne Zusammenfassung