Novel fluorinated block copolymer architectures fuelled by atom transfer radical polymerization

Block copolymers based on poly(pentafluorostyrene), PFS, in various numbers and of different lengths, and polystyrene are prepared by atom transfer radical polymerization (ATRP). Di- and triblock copolymers with varying amounts of PFS were synthesized employing either 1-phenylethylbromide or 1,4-dibromoxylene as initiators for ATRP. Diverse bromo(ester) (macro)initiators were also devised and involved in the formulation of fluorinated pentablock as well as amphiphilic triblock copolymers with a central polyether segment. Amphiphilic star-shaped fluoropolymers, hydrophobic fluorinated nanoparticles, or segmented fluorinated star-shaped block copolymers are further designed by use of different multifunctional initiators. The composition of the novel materials with PFS is determined by combination of SEC and ¹H NMR. Glass transition temperatures and thermal stabilities of the hydrophobic star-shaped PFSs on a six arm dipentaerythritol core are investigated in a wide range of molecular masses and further discussed.     

磷化氢与环烯烃反应的原位^3^1P NMR研究

本文应用加压原位核磁共振波谱技术, 在反应温度50-70℃、反应压力1.0-2.0MPa, 氘代苯为溶剂, 偶氮二异丁腈为引发剂的条件下, 考察了磷化氢与环烯烃1, 5-环辛二烯、双环戊二烯、1, 3-环己二烯、1, 4-环己二烯及1, 5, 9-环十二三烯的反应。实验结果表明, 磷化氢与1, 5-环辛二烯反应主要生成双环膦杂环壬烷; 与其它环烯烃均不生成膦杂环化合物, 仅为一取代伯膦或二取代仲膦产物。磷化氢与环烯烃反应仍为串行机理。     

选相原位法合成立方氮化硼的关键影响因素

利用选相原位法在水溶液中成功制备出了立方氮化硼晶体，对反应条件进行了优化。结果表明，利用选相原位法合成立方氮化硼的最佳实验条件是：反应压力为10.0 MPa，在氯离子加入下利用混合氮源进行反应。在该条件下得到了纯相的立方氮化硼晶体。     

Concavine, an unusual diterpenic alkaloid produced by the fungus Clitocybe concava

A novel alkaloid with an unprecedented ring system consisting of a dodecahydro-7-oxa-9a-aza-benzo[a]azulene ring (1), has been isolated from cultures of Clitocybe concava (Basidiomycetae). Its structure and relative stereochemistry were elucidated on the basis of spectroscopic data. Concavine presents a weak antibacterial activity.     

In situ sensing of the middle atmosphere with balloonborne near-infrared laser diodes

Since 1997, two near-infrared laser diode sensors have been developed with the support of the CNES, the French space agency, to provide in situ data of H(2)O, CH(4) and CO(2) in the middle atmosphere. The realized instruments were flown from stratospheric balloons within the framework of European campaigns for the study of stratospheric ozone and water vapor and were involved in the validation of the ODIN and ENVISAT satellites. In this paper, we describe the developed laser probing technique, we report atmospheric measurements and finally we discuss future perspectives, particularly the in situ laser sensing of the lower atmosphere of Mars and the implication of the laser hygrometers in balloon campaigns at mid-latitudes and tropical regions to investigate the sources and sinks of stratospheric H(2)O.     

FeZSM－5沸石上乙苯的吸附态及氧化脱氢

ＦｅＺＳＭ－５吸附乙苯前后的ＩＲ、ＸＰＳ、ＥＳＲ及Ｍｏｓｓｂａｕｅｒ谱表明，乙苯分子的侧链和苯环与ＦｅＺＳＭ－５的活性位（以Ｆｅ为中心的结构单元）同时发生配位络合作用，减弱了乙苯分子侧链的α和β位Ｃ－Ｈ键，使其活化，在氧存在下易发生氧化脱氢反应生成苯乙烯．Ｆｅ（Ⅲ）是乙苯氧化脱氢的活性中心，尤其是骨架不饱和配位的Ｆｅ（Ⅲ）对活化乙苯分子起到了关键作用，碱金属平衡阳离子起到了助催化剂的作用．骨架Ｆｅ（Ⅲ）比非骨架Ｆｅ（Ⅲ）具有更高的氧化脱氢活性     

Atom transfer radical polymerization of 1-phenoxycarbonyl ethyl methacrylate monomer

Atom transfer radical polymerization conditions with copper(I) bromide/2,2^′-bipyridine (Cu/2,2^′-bpy) as the catalyst system were employed for the homopolymerization and random copolymerization of 1-phenoxycarbonyl ethyl methacrylate (PCMA) with methyl methacrylate (MMA). Temperature studies indicated that the polymerizations occurred smoothly in bulk at 110 °C. Poly(PCMA)(polydispersity index=1.27) homopolymer was characterized and then used as macroinitiator for increasing its molecular weight. The homopolymerization of PCMA was also carried out under free radical conditions using 2,2^′-azobisisobutyronitrile as an initiator.The monomer and polymers were characterized by FT-IR and ¹H and ¹³C-NMR techniques. The glass transition temperatures, the solubility parameters and average-molecular weights of the polymers were determined. Thermal stabilities of the polymers were given as compared with each other by using TGA curves. Thermal degradation products of poly(PCMA)s obtained by ATRP and free radical polymerization were compared with each other by using ¹H-NMR technique.     

The Reactivity of Cr‐Te Superlattice Reactants and of Co‐deposited Cr‐Te Films: Studies with in‐situ X‐ray Diffractometry

The reactivity of a Cr‐Te multilayer film consisting of 326 Cr/Te double‐layers with about 88(3) at% Te was investigated with in‐situ X‐ray diffraction. The occurrence of a superstructure reflection caused by the multilayer system is observed. During the annealing procedure between 80 and 90 °C the layer‐by‐layer arrangement is destroyed and elemental Te crystallizes. After 6 h isothermal annealing at 140 °C CrTe₃ starts to crystallize. The amount and the crystal size of CrTe₃ increase with raising temperature and Te is consumed during the growth process. At 220 °C the formation of crystalline Cr₂Te₃ is observed and between 220 and 260 °C CrTe₃ is completely decomposed into Cr₂Te₃. The two Cr tellurides grow as highly textured materials. The size of CrTe₃ crystals is significantly larger than that of Cr₂Te₃. For a co‐deposited Cr‐Te film with composition 77(3) at% Te the tri‐telluride and elemental Te crystallize simultaneously. The texture of CrTe₃ is less pronounced and different reflections of the tri‐telluride occur besides the (h00)‐reflections. Up to 160 °C a pronounced increase of the crystallite size is observed and the crystals are significantly larger than those obtained with the multifilm sample. At 130 °C the crystallization kinetics seem to be controlled by nucleation.     

High-temperature transformations of Cu-rich hydrotalcites

CuM(II)Al ternary hydrotalcites (M(II) = Ni, Co and Mg) with a (Cu+M(II))/Al atomic ratio of 3.0 and Cu/M(II) atomic ratio of 5.0 were synthesized by coprecipitation under low supersaturation. Powder X-ray diffraction of the as-synthesized samples showed a pattern characteristic of hydrotalcite-like (HT-like) structure (JCPDS: 41-1428). Thermal analyses of these samples showed four stages of weight loss/heat change when recorded in nitrogen. Analysis of the evolved gases characterized the nature of these transformations. The thermoanalytical effects differed significantly especially for the high-temperature transformations, when the treatment was performed in oxygen. In situ powder X-ray diffraction of the samples was carried out to elucidate the phase evolution of these compounds. Surprisingly formation of CuO was noted at temperatures around 200°C well below the destruction of the layered network. The nature of the resulting phases varied with both the nature of the co-bivalent metal ion and the heating atmosphere. FT-IR spectroscopy confirmed the retention of carbonate ions at higher temperatures (above 700°C), although the concentration of carbonate anion (most likely unidentate) varied with the calcination temperature. The crystallinity of CuO increased significantly above 600°C, probably through dissociation of copper oxycarbonate. Significant differences in the thermal transformation temperatures (for the third and the fourth transformations) of these samples containing different co-bivalent metal ions were not observed. This suggests that an association of the co-bivalent metal ions and/or trivalent metal ion in this phase is unlikely. A plausible thermal evolution scheme of these hydrotalcites is proposed.     

ATRP grafting of styrene from benzyl chloride functionalized polysiloxanes: An AFM and TGA study of the Cu(0)/bpy catalyst

Various combinations of Cu(0), CuCl, 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) were used as catalysts for the grafting polymerizations of styrene from polysiloxane macroinitiators functionalized with benzyl chloride. While Cu(0)/bpy alone promotes the grafting, narrower polydispersities were obtained in the presence of CuCl. Analysis of the Cu(0) surface before and after polymerization by a combination of AFM, TGA and FTIR investigations reveals the formation of bpy or phen films on Cu(0). In the presence of CuCl, the ligand film appears decorated with CuCl particles which increase in size with increasing the CuCl concentration. The initial layer occurs most likely as a result of complexation between the ligands and the Cu(0) surface and acts as a support for the rest of the film. These observations are consistent with the film formation on Cu(0) from related nitrogen donors and indicate that the reactivity of the Cu surface may depend not only on its prior treatment but also on the deposition of ligands from the reaction mixture.