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781.
Sandrine Duluard Joseph Grondin Jean‐Luc Bruneel Isabelle Pianet Axelle Grlard Guy Campet Marie‐Hlne Delville Jean‐Claude Lassgues 《Journal of Raman spectroscopy : JRS》2008,39(5):627-632
The Raman spectra of (1 − x)(BMITFSI), xLiTFSI ionic liquids, where 1‐butyl‐3‐methylimidazolium cation (BMI+) and bis(trifluoromethane‐sulfonyl)imide anion (TFSI−) are analyzed for LiTFSI mole fractions x < 0.4. As expected from previous studies on similar TFSI‐based systems, most lithium ions are shown to be coordinated within [Li(TFSI)2]− anionic clusters. The variation of the self‐diffusion coefficients of the 1H, 19F, and 7Li nuclei, measured by pulsed‐gradient spin‐echo NMR (PGSE‐NMR) as a function of x, can be rationalized in terms of the weighted contribution of BMI+ cations, TFSI− ‘free’ anions, and [Li(TFSI)2]− anionic clusters. This implies a negative transference number for lithium. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
782.
4,4′‐Methylenebis(2‐tert‐butylaniline) was synthesized and reacted with pyromellitic dianhydride to produce a polyimide that showed excellent solubility in conventional organic solvents. Solutions of this polyimide could be cast into transparent, flexible and tough films. The number‐average molecular weight, as determined by means of gel permeation chromatography, was 8.9×104 g/mol and the polydispersity index was 1.97. The glass transition temperature was found to be 217°C. The polyimide did not show appreciable decomposition up to 500°C under a nitrogen atmosphere. 相似文献
783.
Jos Luis de la Fuente Marta Fernndez‐García Marina Fernndez‐Sanz Enrique Lpez Madruga 《Macromolecular rapid communications》2001,22(17):1415-1421
Methyl methacrylate and butyl acrylate monomers are copolymerized by atom‐transfer radical polymerization, affording polymers with well‐controlled molecular weight and low polydispersity. A kinetic analysis of this system is compared with the corresponding free‐radical polymerization system. The copolymerization rate follows an opposite trend to that observed in conventional copolymerization. This fact is attributed to a smaller population of radicals generated in the reaction, since the relative fraction of propagating radicals is the same as that in classical copolymerization. 相似文献
784.
Ludivine Bouvier-Fontes Rosangela Pirri Gurutze Arzamendi José M. Asua Jose R. Leiza 《Macromolecular Symposia》2004,206(1):149-164
The seeded semibatch emulsion polymerization of butyl acrylate (BA) with allyl methacrylate (AMA) and butanediol diacrylate (BDA) was used to study the influence of the crosslinkers on the kinetics, branching and crosslinking density, gel fraction and sol MWD produced during the experiments carried out at 80°C using potassium persulfate as initiator. Surprisingly, the most reactive crosslinker, BDA, produced the less crosslinked, branched and gel containing polymer. These results were explained with the help of a mathematical model in terms of cyclization reactions and diffusion controlled propagation and termination reactions. 相似文献