Modified cubic spherosilicates as macroinitiators for the synthesis of inorganic–organic starlike polymers

Modified cubic spherosilicate cages of the type [Si₈O₂₀]^8? were used as rigid, inorganic cores for the synthesis of macroinitiators for thermal and photoinduced free radical and controlled radical polymerizations. Two different routes to these macroinitiators were investigated: the direct modification of the octaanion with chlorosilane‐functionalized initiators and the hydrosilation of SiH‐substituted cages. The latter synthesis of the macroinitiators resulted in more defined reaction products. With these compounds, the polymerizations of styrene and methyl methacrylate were carried out. The free radical polymerizations showed broad polydispersities based on coupling reactions, whereas the copper‐mediated atom transfer radical polymerizations (ATRP) revealed that good polymerization control could be achieved with the prepared initiators. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3858–3872, 2002     

Interactions of He atoms with Xe plated graphite: unified treatment of scattering and adsorbate dynamics based on method of coupled channels

Interactions of He atoms with surfaces have been in the focus of surface scientists for more than seventy years. Depending on the types of the studied problems, and on the algorithms available for their assessment, the accuracy of model calculations aiming at the interpretations of the various aspects of He-atom scattering and dynamics in the adsorbed phase have greatly varied during that period. In this article, we describe the application of a numerical algorithm based on the coupled-channel method that proves very accurate in the calculations of eigen-states and eigen-energies of He atoms interacting with strongly corrugated surfaces. The algorithm is applied to compute diffraction spectra characteristic of thermal energy He-atom scattering from a monolayer of Xe atoms adsorbed on (0 0 0 1) surface of graphite, and the thermodynamical quantities describing a quasi-two-dimensional gas of He atoms adsorbed on the same surface. The usefulness of the developed approach is illustrated in comparisons of the theoretical results with the available experimental data.     

C60F14OFPh3, a fluoroxy derivative of C60F15Ph3; evidence for the presence of ‘missing’ fluorine through restricted rotation of a phenyl group

From the reaction of C₆₀F₁₈ with benzene in the presence of SbCl₅ we have isolated a compound of 1252 amu indicated to be C₆₀F₁₄OFPh₃, a fluoroxyfullerene. Temperature-variable ¹H NMR shows that one phenyl group suffers restricted rotation on cooling to 218 K, attributed to the presence of the OF group which, as in the case of the recently characterised C₆₀F₁₇OF, fails to give a signal for this group in the ¹⁹F NMR. We have isolated also, C₆₀F₁₄O₂FPh₃ (1268 amu) a mixture of oxahomo derivatives of C₆₀F₁₄OFPh₃ arising from oxygen insertion into FCCF bonds. Theoretical calculations for C₆₀F₁₄OFPh₃ indicate that the phenyl group nearest to the OF group is twisted out of the plane containing the other two.     

含NS和NNSS供电子原子的钌(Ⅱ)羰基配合物

通过[RuHCl(CO)(PPh₃)₂(B)] (B=PPh₃, 吡啶 (py), 哌啶 (pip), 吗啉 (morph))与适当的席夫碱按1∶1的物质的量的比反应，合成了二齿和四齿席夫碱钌(Ⅱ)配合物。所用席夫碱配体通过S-苄基二硫代肼基甲酸酯与2,3-丁二酮(物质的量的比分别为1∶1和1∶2)的缩合反应制得。通过元素分析和多种物理化学方法对钌(Ⅱ)配合物和其席夫碱配体进行了表征。钌(Ⅱ)配合物为六配位的反磁性物质。用三种细菌对席夫碱配体及其钌(Ⅱ)配合物的抗微生物活性进行了筛选试验。     

The polarisability of Hg and the ground-state interaction potential of Hg2

Summary The Hg atom electric polarisability at MP3, MP4, QCISD or QCISD(T) level using a 20 valence-electron pseudopotential and a (9s8p7d2f)/[7s6p4d2f] basis set converges and agrees with experiment. The calculated Hg₂ X ¹ V (R) at the same level is roughly half of experiment atR _e but twice as large as the experimentalC ₆ at largeR.Dedicated to Inga Fischer-Hjalmars whose wit and charm made Quantum Chemistry a better place On leave of absence from: Department of Chemistry, Peking University, Beijing 100871, People's Republic of China     

Linear Approximation of Basis Set Orbital Exponents for Isoelectronic Series of Atoms

The orbital exponents of Slater type atomic orbitals (AOs) in isoelectronic series of atoms may be approximated by the linear dependence on the nuclear charge using a technique developed for optimization of AO basis sets in Hartree–Fock–Roothaan calculations. This approach yields the analytical Hartree–Fock wave functions for any ion in the isoelectronic atomic series without optimization of orbital exponents. The approximated linear equations for atomic orbital basis sets of B, C, O, and F in the ground state are presented as an example.     

纳米孔阵列阳极氧化铝膜的制备和表征

本文通过在0℃、0.5mol·L^-1的草酸溶液中阳极氧化高纯铝片的方法制得了阳极氧化铝(AAO)膜，并用扫描电子显微镜(SEM)和原子力显微镜(AFM)对AAO膜的形貌和结构进行了表征。结果表明，阻挡层AAO膜中大小一致的膜胞在铝/氧化铝界面上排成六方形阵列;有孔层AAO膜中含有高度有序的纳米孔阵列和膜胞阵列，并且孔的直径和膜胞的尺寸都具有较窄的分布。另外，考察了阳极氧化电压对膜胞尺寸、孔径大小、孔密度和膜胞密度的影响，表明在一定的电压范围内，膜胞和孔径都随电压的升高而增大，而孔密度和膜胞密度却随电压的升高而减小。     

Synthesis of proton‐conducting membranes by the utilization of preirradiation grafting and atom transfer radical polymerization techniques

The atom transfer radical polymerization (ATRP) of styrene onto poly(vinylidene fluoride)‐graft‐poly(vinylbenzyl chloride) (PVDF‐g‐PVBC) membranes was investigated. Novel membranes were designed for fuel‐cell applications. The benzyl chloride groups in the PVDF‐g‐PVBC membranes functioned as initiators, and a Cu‐based catalytic system with the general formula Cu(n)X_n/ligand [where X is Cl or Br and the ligand is 2,2′‐bipyridyl (bpy)] was employed for the ATRP. In addition, 10 vol % dimethylformamide was added for increased solubility of the catalyst complex in styrene. The system was homogeneous, except for the membrane, when the initiator/copper halide/ligand/monomer molar ratio was 1/1/3/500. As anticipated, the fastest polymerization rate of styrene was observed with the copper bromide/bpy‐based catalyst system. The reaction rate was strongly temperature‐dependent within the studied temperature interval of 100–130 °C. The degree of grafting increased linearly with time, thereby indicating first‐order kinetics, regardless of the polymerization temperature. Furthermore, 120 °C was the maximum polymerization temperature that could be used in practice because the membrane structure was destroyed at higher temperatures. The degree of styrene grafting reached 400% after 3 h at 120 °C. Such a high degree of grafting could not be reached with conventional uncontrolled radiation‐induced grafting methods because of termination reactions. On the basis of an Arrhenius plot, the activation energy for the homogeneous ATRP of styrene was 217 kJ/mol. The prepared membranes became proton‐conducting after sulfonation of the polystyrene grafts. The highest conductivity measured for the prepared membranes was 70 mS/cm, which is comparable to the values normally measured for commercial Nafion membranes. The scanning electron microscopy/energy‐dispersive X‐ray results showed that the membranes had to be grafted through the matrix with both PVBC and polystyrene to become proton‐conducting after sulfonation. In addition, PVDF‐g‐[PVBC‐g‐(styrene‐block‐tert‐butyl acrylate)] membranes were also synthesized by ATRP. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 591–600, 2002; DOI 10.1002/pola.10146     

Synthesis and characterization of well‐defined ABC‐type triblock copolymers via atom transfer radical polymerization and stable free‐radical polymerization

An asymmetric difunctional initiator 2‐phenyl‐2‐[(2,2,6,6 tetramethylpiperidino)oxy] ethyl 2‐bromo propanoate ( 1 ) was used for the synthesis of ABC‐type methyl methacrylate (MMA)‐tert‐butylacrylate (tBA)‐styrene (St) triblock copolymers via a combination of atom transfer radical polymerization (ATRP) and stable free‐radical polymerization (SFRP). The ATRP‐ATRP‐SFRP or SFRP‐ATRP‐ATRP route led to ABC‐type triblock copolymers with controlled molecular weight and moderate polydispersity (M_w/M_n < 1.35). The block copolymers were characterized by gel permeation chromatography and ¹H NMR. The retaining chain‐end functionality and the applying halide exchange afforded high blocking efficiency as well as maintained control over entire routes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2025–2032, 2002     

Chain‐transfer reaction in the radical polymerization of di‐n‐butyl itaconate at high temperatures

Radical polymerizations of di‐n‐butyl itaconate were investigated. Unexpected resonances (C resonances) were observed in ¹³C NMR spectra of C?O of poly(di‐n‐butyl itaconate)s [poly(DBI)s] obtained at temperatures higher than 60 °C, although two kinds of carbonyl groups showed splittings due to triad tacticities in the spectra of polymers obtained at lower temperatures. The poly(DBI)s formed by the different kinds of initiators or formed in the presence of chain‐transfer agents showed hardly any changes in the intensities of the C resonances; this indicated that the C resonances were not due to the structures formed through initiating and terminating reactions. The poly(DBI)s obtained at different yields showed only a slight increase in the intensities of the C resonances with the yield, which suggested that the C resonances were not attributable to the intermolecular chain‐transfer reaction to the monomer and/or polymer. However, the intensities of the C resonances significantly increased with a decreasing feed monomer concentration; this suggested that intramolecular chain‐transfer reactions took place at high temperatures. Furthermore, a Cu complex‐catalyzed atom transfer radical polymerization mechanism was revealed to be effective for suppressing the intramolecular chain‐transfer reaction at 60 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2415–2426, 2002