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71.
Cong‐Duan Vo Julien Rosselgong Steven P. Armes Nicola Tirelli 《Journal of polymer science. Part A, Polymer chemistry》2010,48(9):2032-2043
Homopolymerization and diblock copolymerization of 2‐hydroxypropyl acrylate (HPA) has been conducted using reversible addition fragmentation chain transfer (RAFT) chemistry in tert‐butanol at 80 °C. PHPA homopolymers were obtained with high conversions and narrow molecular weight distributions over a wide range of target degrees of polymerization. Like its poly(2‐hydroxyethyl methacrylate) isomer, PHPA homopolymer exhibits inverse temperature solubility in dilute aqueous solution, with cloud points increasing systematically on lowering the mean chain length. The nature of the end groups is shown to significantly affect the cloud point, whereas no effect of concentration was observed over the PHPA concentration range investigated. Various thermoresponsive PHPA‐based diblock copolymers were prepared via one‐pot syntheses in which the second block was either permanently hydrophilic or pH‐responsive. Preliminary studies confirmed that poly(ethylene oxide)‐poly(2‐hydroxypropyl acrylate) (PEO45‐PHPA48) and poly(2‐hydroxypropyl acrylate)‐ poly(2‐hydroxyethyl acrylate) (PHPA49‐PHEA68)diblock copolymers formed well‐defined PHPA‐core micelles in 10 mM sodium nitrate solution at 40 °C and 70 °C with mean hydrodynamic diameters of 20 nm and 35 nm, respectively. In contrast, most other PHPA‐based diblock copolymers investigated formed larger colloidal aggregates in 10 mM NaNO3 solution at elevated temperatures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2032–2043, 2010 相似文献
72.
Paul Barbic Leo Binder Susanne Voß Ferdinand Hofer Werner Grogger 《Monatshefte für Chemie / Chemical Monthly》2001,132(4):465-472
Summary. Thin-film electrodes allow the manufacturing of flat batteries of variable design. Their electric performance is better than
that of customary cells because of a larger contact area between anode and cathode and better utilization of the electrochemically
active materials. Bipolar thin-film electrodes for the rechargeable alkaline zinc/manganese dioxide system were assembled
using graphite-filled plastics (high-density polyethylene and polyisobutylene). In a different approach, extremely thin electrodes
were obtained using 25 μm thick foils made of non-conductive micro-porous polypropylene. The electroactive materials were
electrolytically deposited into the pores of the previously metallized foil, providing the required conductive connection
through the plastic matrix by themselves. Cycle behavior, cumulated capacities, and energies of batteries with up to two bipolar
units were measured. At this early stage of development, batteries based on graphite-filled polymer foils showed better results
with regard to storage capacity per unit area and to cycle life. Prototypes based on micro-porous polypropylene suffered from
the relatively small fraction of pore volume available for the deposition of active material (about 38%) and from current
collector corrosion.
Received May 30, 2000. Accepted December 18, 2000 相似文献
73.
E. Nguyen Cong Duc L. Fournier C. Levecq B. Lesjean P. Grelier A. Tazi-Pain 《Journal of membrane science》2008
The better understanding of the effective air distribution inside a membrane cassette is a particular challenge in submerged membrane bioreactor. The present study is the first one that investigates the hydrodynamics of the coarse bubbles flow inside a hollow fibre membranes cassette. The experimental investigations were carried out in a reactor equipped with commercial modules from ZENON ZeeWeed® 500d. A bi-optical probe was used to measure the bubble size, the bubble velocity and the gas hold-up at different locations between the modules and for three different gas flow rates. These local measurements gave significant information about the lateral distribution of the air and its evolution with the height on the surface of the membrane modules, which can impact on the filtration performance and are the first step to an optimisation of the aeration system and module geometry. 相似文献
74.
C. Tomas J.P. Girardeau-Montaut M. Afif M. Romand M. Charbonnier T.M. Duc 《Applied Physics A: Materials Science & Processing》1997,64(5):467-471
3+ :YAG laser with 5th harmonic generator, generating 16 ps duration pulses at 213 nm, with energies up to 0.5 mJ. Experimental results concerning
the action of laser pulses, as well as the effects of residual pressure on the cleanliness of the photocathodes surface are
presented and discussed. Influence of laser pulses and residual pressure on the work function of the metal are also investigated.
Received: 15 April 1996/Accepted: 5 November
1996 相似文献
75.
76.
This paper reports a new Cartesian‐grid collocation method based on radial‐basis‐function networks (RBFNs) for numerically solving elliptic partial differential equations in irregular domains. The domain of interest is embedded in a Cartesian grid, and the governing equation is discretized by using a collocation approach. The new features here are (a) one‐dimensional integrated RBFNs are employed to represent the variable along each line of the grid, resulting in a significant improvement of computational efficiency, (b) the present method does not require complicated interpolation techniques for the treatment of Dirichlet boundary conditions in order to achieve a high level of accuracy, and (c) normal derivative boundary conditions are imposed by means of integration constants. The method is verified through the solution of second‐ and fourth‐order PDEs; accurate results and fast convergence rates are obtained. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
77.
Optical spectra of highly excited quantum wires at low temperatures have been studied within the dynamical screening approximation. We found a strong Fermi-edge singularity (FES) in the photoluminescence spectra. The spectral shape and FES intensity strongly depend on temperature in agreement with recent experimental results. 相似文献
78.
79.
We study a quasilinear elliptic equation in the unit ball ofℝ
m
. Using this result we get the existence of graphs with prescribed curvature on hyperbolic spacesℍ
m
inℍ
m
×ℝ. 相似文献
80.
I. A. Vasil’eva N. A. Voĭtova R. N. Nurmukhametov L. I. Belenky S. I. Luĭksaar 《Optics and Spectroscopy》2007,103(4):577-584
The fine-structure fluorescence and fluorescence excitation spectra of conjugated chain compounds, namely, 2,5-bis(5-phenyl-1,3,4-oxadiazol-2-yl)furan (PDFDP) and 2,5-bis[5-(2,4-dimethylphenyl)-1,3,4-oxadiazol-2-yl]furan (XDFDX), were obtained by the Shpolskii method in an n-octane matrix at a temperature of 4.2 K. These spectra were simulated by representing the band of each of the vibronic transitions as the sum of a zero-phonon line and a phonon wing with the corresponding parameters, such as the half-widths of the spectral lines and the Debye-Waller factors. The results obtained made it possible to estimate the relative intensities of the vibronic transitions between the S 0 and S*1 states. The anharmonicity revealed in the conjugate spectra of fluorescence and fluorescence excitation of the PDFDP and XDFDX compounds was explained in terms of the interference of the Franck-Condon and Herzberg-Teller interactions occurring in the molecules under investigation. The influence of the substitution of the furan heterocycle (F) for the central benzene ring (P) in 1,4-bis-(5-phenyl-2-oxadiazolyl)benzene (PDPDP) on the parameters of the intramolecular interactions responsible for the formation of the vibronic spectra was considered. 相似文献