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Analytical and Bioanalytical Chemistry - 相似文献
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Dendronized Hyperbranched Macromolecules: Soft Matter with a Novel Type of Segmental Distribution 下载免费PDF全文
Priv.‐Doz. Dr. Albena Lederer Prof. Dr. Walther Burchard Tobias Hartmann Johannes S. Haataja Dr. Nikolay Houbenov Andreas Janke Dr. Peter Friedel Dr. Ralf Schweins Dr. Peter Lindner 《Angewandte Chemie (International ed. in English)》2015,54(43):12578-12583
Dendronization of a hyperbranched polyester with different generation dendrons leads to pseudo‐dendritic structures. The hyperbranched core is modified by the divergent coupling of protected monomer units to the functional groups. Compared to dendrimers, the synthetic effort is significantly less, but the properties are very close to those of high‐generation dendrimers. The number of functional groups, molar mass, and rheology behavior even in the early generation (G1–G4) pseudo‐dendrimers strongly resembles the behavior of dendrimers in higher generations (G5–G8). Comparison of the segmental and internal structure with perfect dendrimers is performed using SANS, dynamic light scattering and viscosity analysis, microscopy and molecular dynamics simulation. The interpretation of the results reveals unique structural characteristics arising from lower segmental density of the core, which turns into a soft nano‐sphere with a smooth surface even in the first generation. 相似文献
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A. Zaviyalov R. Iliew O. Egorov F. Lederer 《Applied physics. B, Lasers and optics》2011,104(3):513-521
We numerically investigate the formation of soliton pairs (bound states) in mode-locked fiber ring lasers in the normal dispersion domain. In the distributed mathematical model (complex cubic-quintic Ginzburg–Landau equation), we observe a discrete
family of soliton pairs with equidistantly increasing peak separation. We show that stabilization of previously unstable bound
states can be achieved when the finite relaxation time of the saturable absorber is taken into account. The domain of stability
can be controlled by varying this relaxation time. Furthermore, we investigate the parameter domain where the region of stable
bound states does not shrink to zero for vanishing absorber recovery time corresponding to a laser with an instantaneous saturable absorber. For a certain domain of the small-signal gain, we obtain a robust first level bound state with almost
constant separation where the phase of the two pulses evolves independently. Moreover, their phase difference can evolve either
periodically or chaotically depending on the small signal gain. Interestingly, higher level bound states exhibit a fundamentally
different dynamics. They represent oscillating solutions with a phase difference alternating between zero and π. 相似文献
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Mireia Morell Brigitte Voit Xavier Ramis Àngels Serra Albena Lederer 《Journal of polymer science. Part A, Polymer chemistry》2011,49(14):3138-3151
Well‐defined multiarm star block copolymers poly(glycidol)‐b‐poly(methyl methacrylate) (PGOHBr‐b‐PMMAx) with an average number of PMMA arms of 85, 55, and 45 have been prepared. The core‐first approach has been selected as the methodology using atom transfer radical polymerization (ATRP) of MMA from an activated hyperbranched poly(glycidol) as the core. These activated hyperbranched macroinitiators were prepared by esterification of hyperbranched poly(glycidol) (PGOH) with 2‐bromoisobutyryl bromide. The effect of monomer/initiator ratio, catalyst concentration, time, temperature, and solvent on the growing of the arms has been studied in detail in order to optimize the process and to diminish the radical‐radical coupling. The final products and intermediates were characterized by means of size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) and Fourier transform‐infrared (FTIR) spectroscopy. The length of PMMA arms was determined by SEC after cleavage of ester bond linked to PGOH core. Glass transition temperature (Tg), thermal stability and rheological properties of the multiarm star copolymers were also studied. Finally, tapping mode atomic force microscopy (TMAFM) allowed the clear visualization of nano‐sized particles (80–200 nm) corresponding to individual star molecules. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
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Thin film tandem solar cells made of amorphous and microcrystalline silicon provide renewable energy at the benefit of low material consumption. As a drawback, these materials do not posses the high carrier mobilities of their crystalline counterpart which limits the feasible material thickness. For maintaining the light absorption as high as possible, photon management is required. Here we show that metallic nanodiscs that sustain localized plasmon polaritons can increase the efficiency of such solar cells if they are incorporated into the dielectric intermediate reflector separating the top and the bottom cell. We provide quantitative estimates for the possible absorption enhancement of optimized bi-periodic nanodiscs that are feasible for fabrication. Emphasis is also put on discussing the impact of obliquely incident sun light on the solar cell performance. 相似文献