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排序方式: 共有727条查询结果,搜索用时 796 毫秒
721.
Laurence Couvreur Gwenaelle Piteau Patrice Castignolles Matthew Tonge Bernard Coutin Bernadette Charleux Jean‐Pierre Vairon 《Macromolecular Symposia》2001,174(1):197-208
Pulsed‐laser photoinitiated polymerization was used to determine, in toluene solution, the propagation kinetic parameters of a series of acrylates with increasing size of the alkyl side group. Transfer to monomer and to toluene did not occur significantly in our PLP conditions and our temperature range since no broadening of the MMD was observed, allowing generally to work with two inflection points. In contrast, depending on the nature of the acrylate and on the PLP conditions, transfer to polymer, and thus long chain branching, can critically interfere. Indeed, the Mark‐Houwink‐Sakurada parameters, which are used to calculate the absolute molar mass at the inflection point, strongly depend on the polymer structure and thus, should be carefully measured for each PLP sample. Although still preliminary, the results show that the kps measured in toluene solution present a tendency to continuously decrease when increasing the size of the side group. This observation is conflicting with the reported behaviour for PLP experiments in bulk, revealing a possible solvent effect. 相似文献
722.
Anatoly N. Nikitin Patrice Castignolles Bernadette Charleux Jean‐Pierre Vairon 《Macromolecular theory and simulations》2003,12(6):440-448
A new approach for the simulation of PLP (pulsed laser polymerization) is presented. This approach allows one to obtain new analytical solutions for different polymerization schemes, including either chain transfer to the monomer or intramolecular chain transfer to the polymer. The first results of the simulation of PLP experiments on n‐butyl acrylate at 20 °C and ambient pressure are presented.
723.
Patrice Mélé Claude Da Silva Sandrine Marceau David Brown Yves De Puydt Nicole Dominique Albérola 《Macromolecular Symposia》2003,194(1):185-190
The aim of this work is to analyse the influence of both silica content and the presence of a silane coupling agent on the viscoelastic behaviour of silica filled rubber. It is well-known that changes in the dynamic mechanical properties of filled rubber could result from either the mechanical coupling between phases and/or interface effects. Micro mechanical modelling, taking morphological analysis into account, will be used to separate these two effects and allows us to assess the actual properties of the polymer close to the silica surface. 相似文献
724.
Dr. Supriya Ghosh Dr. Debkumar Rana Dr. Bapi Pradhan Dr. Patrice Donfack Prof. Dr. Johan Hofkens Prof. Dr. Dr. Arnulf Materny 《Chemphyschem》2023,24(21):e202300303
In recent years, there has been an impressively fast technological progress in the development of highly efficient lead halide perovskite solar cells. Nonetheless, the stability of perovskite films and associated solar cells remains a source of uncertainty and necessitates sophisticated characterization techniques. Here, we report low- to mid-frequency resonant Raman spectra of formamidinium-based lead mixed-halide perovskites. The assignment of the different Raman lines in the measured spectra is assisted by DFT simulations of the Raman spectra of suitable periodic model systems. An important result of this work is that both experiment and theory point to an increase of the stability of the perovskite structure with increasing chloride doping concentration. In the Raman spectra, this is reflected by the appearance of new lines due to the formation of hydrogen bonds. Thus, higher chloride doping results in less torsional motion and lower asymmetric bending contributing to higher stability. This study yields a solid basis for the interpretation of the Raman spectra of formamidinium-based mixed-halide perovskites, furthering the understanding of the properties of these materials, which is essential for their full exploitation in solar cells. 相似文献
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