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81.
Dithiocarbamate functions were incorporated into different polyacrylamide matrices crosslinked with a flexible and hydrophilic
crosslinking agent, tetraethyleneglycol diacrylate (TEGDA), and their complexation behaviours were investigated. Crosslinked
polyacrylamides with varying extents of the tetrafunctional TEGDA crosslinks were prepared by free radical solution polymerization
at 60°C using potassium persulphate as initiator in ethanol. The dithiocarbamate functionality was incorporated into these
polyacrylamides by a two-step polymer-analogous reaction involving (i)trans-amidation with ethylenediamine and (ii) dithiocarbamylation of the aminopolyacrylamide with carbon disulphide and alkali.
The complexations of dithiocarbamate with Cu(II), Ni(II), Zn(II), Co(II) and Hg(II) ions were followed under different conditions.
The metal ion intake varied with the extent of the crosslinking agent and the observed trend in complexation is Hg(II) > Cu(II)>
Zn(II)> Co(II)> Ni (II). The time-course of complexation, the possibility of recycling, swelling characteristics, and spectral
and thermal analyses were carried out. The thermal stability increases upon complexation with metal ions. 相似文献
82.
Brad M. Rosen Virgil Percec 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4950-4964
Atom transfer radical polymerization (ATRP) and single electron‐transfer living radical polymerization (SET‐LRP) both utilize copper complexes of various oxidation states with N‐ligands to perform their respective activation and deactivation steps. Herein, we utilize DFT (B3YLP) methods to determine the preferred ligand‐binding geometries for Cu/N‐ligand complexes related to ATRP and SET‐LRP. We find that those ligands capable of achieving tetrahedral complexes with CuI and trigonal bipyramidal with axial halide complexes with [CuIIX]+ have higher energies of stabilization. We were able to correlate calculated preferential stabilization of [CuIIX]+ with those ligands that perform best in SET‐LRP. A crude calculation of energy of disproportionation revealed that the same preferential binding of [CuIIX]+ results in increased propensity for disproportionation. Finally, by examining the relative energies of the basic steps of ATRP and SET‐LRP, we were able to rationalize the transition from the ATRP mechanism to the SET‐LRP mechanism as we transition from typical nonpolar ATRP solvents to polar SET‐LRP solvents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4950–4964, 2007 相似文献
83.
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85.
R. Rehm M. Walther J. Schmitz J. Fleißner F. Fuchs J. Ziegler W. Cabanski 《Opto-Electronics Review》2006,14(1):19-24
The first fully operational mid-IR (3–5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice
showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized.
We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical
characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for
the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active
layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency.
Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays
after implementing this design improvement.
The paper presented there appears in Infrared Photoelectronics, edited by Antoni Rogalski, Eustace L. Dereniak, Fiodor F. Sizov, Proc. SPIE Vol. 5957, 595707 (2005). 相似文献
86.
Fumie Takei Daisuke Kodama Sugiko Nakamura Kiyotaka Onitsuka Shigetoshi Takahashi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):585-595
Aryl isocyanides bearing free‐base and metallo‐porphyrins were prepared and polymerized with a Pd–Pt μ‐ethynediyl complex as the initiator to give polymers with narrow polydispersity indices. The molecular weights of the resulting polymers were precisely controlled by the initial feed ratio of the porphyrin monomer to the initiator. The UV–VIS spectra suggested that the porphyrin pendants are regularly arranged to form stacked columns. Metallo‐porphyrin polymers were also prepared by reacting free‐base porphyrin polymers with metal salts. The successive reactions of free‐base and zinc‐porphyrin monomers resulted in the formation of diblock polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 585–595, 2006 相似文献
87.
Ryosuke Sakai Issei Otsuka Toshifumi Satoh Ryohei Kakuchi Harumi Kaga Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):325-334
The asymmetric polymerization of 4′‐isocyanatobenzo‐18‐crown‐6 with the lithium amide of (S)‐(2‐methoxymethyl)pyrrolidine successfully proceeded to afford end‐functionalized poly(4′‐isocyanatobenzo‐18‐crown‐6) with (S)‐(2‐methoxymethyl)pyrrolidine (polymer 2 ). In the circular dichroism (CD) spectrum of 2 , a clear positive Cotton effect was observed in the range of 240–350 nm corresponding to the absorption of the polymer backbone, indicating that 2 partially formed a one‐handed helical structure, which was preserved by the chirality of (S)‐(2‐methoxymethyl)pyrrolidine bonding to the terminal end in 2 . In the titration experiments for the CD intensity of 2 in the presence of D ‐ and L ‐Phe·HClO4 (where Phe is phenylalanine), a small but remarkable difference was observed in the amount of the chiral guest needed for saturation of the CD intensity and in the saturated CD intensity, indicating that the extremely stable, one‐handed helical part should exist in the main chain of 2 , which was not inverted even when the unfavorable chiral guest for the predominant helical sense, L ‐Phe·HClO4, was added. In addition, helical polymer 2 exhibited a chiral discrimination ability toward racemic guests; that is, the guests were extracted from the aqueous phase into the organic phase with enantiomeric excess. The driving force of the chiral discrimination ability of 2 should certainly be attributed to the one‐handed helical structure in 2 . © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 325–334, 2006 相似文献
88.
89.
本文用数字散斑相关方法测量了五种不同幂硬化指数韧性金属材料(铝和铜),双边裂纹尖端细观区域内应变场.对所得结果用韧性损伤模型进行了分析.在此法中以金属自然表面结构为散斑场,不同加载状态的散斑场进行比较,得到相对变形与应变.图象之间相关性 C 是变形参数或是位移及其导数的泛函.使其相关性 C 取最大值的试凑变形即为其真实变形场.这一方法在细观测量中应用得到满意的结果. 相似文献
90.
Overview: The Potential of silanes for chromate replacement in metal finishing industries 总被引:3,自引:0,他引:3
Wim J. van Ooij Danqing Zhu Vignesh Palanivel J. Anna Lamar Matthew Stacy 《Silicon Chemistry》2006,3(1-2):11-30
Trialkoxysilanes (or silanes) have emerged as a very promising alternative for chromates in metal finishing industries. Compared to the conventional chromating processes, the major merits of silane-based surface treatments include: eco-compliance, easy-control processing, comparable corrosion protection of metals as well as paint adhesion to a variety of topcoats. In this overview paper, we report the recent status of silane studies including results of corrosion performance tests, the mechanism of corrosion protection of metals by silanes and the themal stabilities of silane films. We also address the new fields that we are beginning to explore such as nano-structured silane films, “self-healing” silane films, and “super-primers”. 相似文献