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141.
142.
G. T. Ruiz A. G. Lappin G. Ferraudi 《Journal of polymer science. Part A, Polymer chemistry》2012,50(12):2507-2515
The mechanisms of the redox reactions between a polymer containing Al(III) sulfonated phthalocyanine pendants, (AlIII(?NHS(O2)trspc)2?)2, and radicals have been investigated in this work. Pulse radiolysis and photochemical methods were used for these studies. Oxidizing radicals, OH?, HCO3?, (CH3)2COHCH2?, and N3?, as well as reducing radicals, eaq?, CO2??, and (CH3)2C?OH, respectively accept or donate one electron forming pendent phthalocyanine radicals, AlIII(?NHS(O2)trspc ?)? or 3?. The kinetics of the redox processes is consistent with a mechanism where the pendants react with radicals formed inside aggregates of five to six polymer strands. Electron donating radicals, that is, CO2?? and (CH3)2C?OH, produce one‐electron reduced phthalocyanine pendants that, even though they were stable under anaerobic conditions, donated charge to a Pt catalyst. While the polymer was regenerated in the Pt catalyzed processes, 2‐propanol and CO2 were respectively reduced to propane and CO. The reaction of SO3?? radicals with the polymer stood in contrast with the reactions of the radicals mentioned above. A first step of the mechanism, the coordination of the SO3?? radical to the Al(III), was subsequently followed by the formation of a SO3?? ‐ phthalocyanine ligand adduct. The decay of the SO3?? ‐ phthalocyanine ligand adduct in a ~102 ms time domain regenerates the polymer, and it was attributed to the dimerization/disproportionation of SO3?? radicals escaping from the aggregates of polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
143.
Xiubo Jiang Yi Shi Wen Zhu Yongming Chen Fu Xi 《Journal of polymer science. Part A, Polymer chemistry》2012,50(20):4239-4245
Well‐defined mikto‐topology star polystyrene composed of one cyclic arm and four linear arms was synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) click reaction. First, the bromine‐alkyne α,ω‐linear polystyrenes containing four hydroxyl groups protected with acetone‐based ketal groups were synthesized by ATRP of styrene using a designed initiator. Then, the bromine end‐group was converted to the azide and the linear polystyrene was cyclized intra‐molecularly by the CuAAC reaction. The four hydroxyl groups were released by deprotection and then esterified with 2‐bromoisobutyryl bromide to produce a cyclic polymer bearing four ATRP initiating units. By subsequent ATRP of styrene to grow linear polymers with the cyclic polystyrene as a macroinitiator, the mikto‐topology star polymers were prepared. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
144.
Jennifer N. Cambre Debashish Roy Brent S. Sumerlin 《Journal of polymer science. Part A, Polymer chemistry》2012,50(16):3373-3382
A detailed study of the pH‐ and sugar‐responsive behavior of poly(3‐acrylamidophenylboronic acid pinacol ester)‐b‐poly(N,N‐dimethylacrylamide) (PAPBAE‐b‐PDMA) block copolymers is presented. Reversible addition‐fragmentation chain transfer (RAFT) polymerization of the pinacol ester of 3‐acrylamidophenylboronic acid resulted in homopolymers with molecular weights between 12,000 and 37,000 g/mol. The resulting homopolymers were employed as macro‐chain transfer agents during the polymerization of N,N‐dimethylacrylamide (DMA). Successful chain extension and removal of the pinacol protecting groups to yield poly(3‐acrylamidophenylboronic acid)‐b‐PDMA (PAPBA‐b‐PDMA) with free boronic acid moieties resulted in pH‐ and sugar‐responsive block copolymers that were subsequently investigated for their behavior in aqueous solution. The PAPBA‐b‐PDMA block copolymers were capable of solution self‐assembly due to the PAPBA block being water‐insoluble below its pKa. The resulting aggregates were demonstrated to solubilize and release model hydrophobic compounds, as demonstrated by fluorescence studies. Dissociation of the aggregates was induced by raising the pH above the pKa of the boronic acid residues or by adding sugars capable of forming boronate esters. Aggregate size, dissociation kinetics, and the effect of various sugars were considered. The critical sugar concentration needed to induce aggregate dissociation was tuned by incorporation of hydrophilic DMA units within the PAPBA responsive segment to yield PDMA‐b‐poly(3‐acrylamidophenylboronic acid‐co‐DMA) block copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
145.
《Journal of Coordination Chemistry》2012,65(2):231-239
Abstract The FT-Raman and FT-IR spectra of crystalline glutarimide and its N-deuterated derivative have been recorded in the range 4000-100 cm?1. A complete vibrational assignment is given for all internal modes and is supported by normal coordinate analysis based on a general valence force field. The calculated frequencies are in very good agreement with experiment. A close similarity is found for frequencies of the corresponding vibrations of glutarimide and uracils in the solid state. It is concluded that the strength of hydrogen bonding in glutarimide is very similar to that in crystalline pyrimidine nucleic bases. 相似文献
146.
Anna Hayer Tanguy Van Regemorter Bianca Höfer Chris S. K. Mak David Beljonne Anna Köhler 《Journal of Polymer Science.Polymer Physics》2012,50(5):361-369
Although carbazole‐containing copolymers are frequently used as hole‐transporting host materials for polymer organic light‐emitting diodes (OLEDs), they often suffer from the formation of undesired exciplexes when the OLED is operated. The reason why exciplexes sometimes form for electrical excitation, yet not for optical excitation is not well understood. Here, we use luminescence measurements and quantum chemical calculations to investigate the mechanism of such exciplex formation for electrical excitation (electroplex formation) in a carbazole–pyridine copolymer. Our results suggest that the exciplex is formed via a positively charged interchain precursor complex. This complex is stabilized by interactions that involve the nitrogen lone pairs on both chain segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
147.
Kenzo Sato 《International Journal of Infrared and Millimeter Waves》1986,7(6):927-947
Under the influence of perpendicularly applied positive electro-static field less than 103V/cm to silk fibron textiles, at the high frequency side of the C2–O bending reflection band (450350 cm–1), effect of step creation and step annihilation of the C2–O pseudo dending bands was induced in three stages at 600450 cm–1 region IR spectroscopically relating to the stepnized statistical transfer of the unbonded 2P2, electrons in carbon which present with density of 4.0×1014/cm2 in the surface mono-layer of silk fibroin from the states formed in (–C1–C2–N–)m spiral chains upto the pseudo-bending states formed in C2–O bondings. Fine 90 steps measured overlapping on these four types of C2–O reflection bands were analysed as to consist four step series and they were shown as,y = A·Jm + B cm–1 with A=20, B=521, m=0.55 and J=1, 2...18 for the B-series.And with A=39, B=283, m=0.63 and J=1, 2 ...17 for the C-series.y
J = A·J + B cm–1 with A=11.42, B=201 and J=1, 2...13, for the D-series. And, stepnized C2–O bending bands including that of permanent oscillators and pseudo-bending oscillators induced by the effect of transfer of the unbonded 2P2 electrons in carbon atoms were shown as, EN=A·N2+B·N+C (eV) with A=–1.50×10–3, B=1.65×10–2 and C=2.4×10–2. 相似文献
148.
G K Raju K Venkataramaniah M S Prasad K Narasimhamurty V A Narasimhamurty 《Pramana》1986,26(4):327-335
Differential incoherent scattering cross-section ratios of 279.2 keV photons by zirconium, tin, tantalum, lead and uranium
elements are experimentally determined by comparing the peak areas under the degraded photon energy with that of an equivalent
aluminium foil employing a high resolution 35 c.c. coaxial Ge(Li) detector. Studies have been made in single configuration
in an angular range of 20° to 115°. The results are compared with theoretical values obtained from the non-relativistichfs model of Hubbell and co-workers. The cross-section ratios decrease as the atomic number increases for a given scattering
angle. 相似文献
149.
用ESR方法对9种不同双吡啶高氯酸盐与氧化锌组成的非均相体系的光诱导电子转移过程进行了系统的研究。ZnO-PQ++-胶束-苯的分散系,经350nm~420nm的紫外光照后,PQ++被还原成PQ+。具有大共轭结构的PQ+的ESR信号较强。胶束的存在也可使ESR信号增强。当体系充氧时,PQ+信号消失,并有超氧阴离子基O2·和羟基·OH被检出。 相似文献
150.
由烯烃经一氯硼烷甲硫醚(H2BCl·SMe2)硼氢化和甲醇解制得的二烷基硼酸甲酯6,在50%NaOH和相转移催化剂(TEBA)存在下与氯仿反应,继之氧化,获得了相应的二烷基酮1,二环烷基酮2和3以及脂环酮4.考查了各种参数对反应的影响.讨论了反应机理,为从烯烃出发合成各种类型的酮提供了一条简便新途径. 相似文献