Copolymers of ethylene and butadiene were prepared using the ansa-bisfluorenyl Me2Si(C13H8)2NdR complex in combination with dialkylmagnesium as a chain transfer agent. Thorough kinetic studies and computational mechanistic investigations of this copolymerization reaction were performed. Combined with detailed analyses of the polymer microstructure and chainends, these studies demonstrate that the entitled copolymerization operates according to a living coordinative chain transfer copolymerization of ethylene and butadiene. Besides, in addition to the formation of the previously described 1,2-cyclohexane inner chain cyclic motif, the presence of bicyclic 1,5-decalin units via the formation of transient vinylcyclohexyl-methyl chain-end is discussed in the present communication. The non-accumulation of the vinylcyclohexane motif within the chains is explained by the reversibility of its formation, as interpreted with the help of DFT calculations, or by its rapid conversion into decalin motif after one ethylene insertion. Finally, this study also illustrates the ability of the fluorenyl ligand to adjust its binding mode on demand in order to avoid inhibition of catalyst.

Authors would like to thank Christine LUCAS for help in solid state NMR experiments, C2P2 (Chemistry, Catalysis, Polymer & Processes), UMR 5265 - University of Lyon 1.International audienceA new silicophosphorylated filler was generated in situ in a molten PA66 copolymer during extrusion process with the aim to improve the fire behavior of the matrix. The filler was obtained in one step via hydrolysis-condensation reactions of SiDOPO precursor (DOPO, 9,10-dihydro-9-oxa-10-phosphaphenanthrene). The synthesis of the precursor is reported and characterized by NMR. A Si-29 NMR study of SiDOPO hydrolysis-condensation reactions in N-methylacetamide (NMA) solvent was also conducted. Thermal stability of Cop-PA/SiDOPO composite and the major degradation products were studied by thermogravimetric analysis coupled with Infrared spectrometry (TGA/FTIR). The Pyrolysis Combustion Flow Calorimeter (PCFC) and cone calorimeter were used to investigate the fire behavior of the composite. Results show that the nanocomposite exhibits a little earlier ignition but with a decrease around 33% of the peak of heat release rate (PHRR). The presence at low concentration of silicon (0.65 wt.%) and phosphorus (0.75 wt.%) promotes the formation of an expanded char layer that acts as a barrier. A reduction of about 18% in effective heat of combustion (EHC) values suggests an additional flame inhibition effect of phosphorus in the gas phase

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