Summary: Di‐polyethylenyl magnesium compounds, obtained by a transition metal catalyzed chain growth reaction on butyloctyl magnesium, are reacted with a range of disulfides of thiocarbonylated compounds (RC(S)SSC(S)R). Xanthate, dithiocarbamate, dithioester, and trithiocarbonate‐functionalized polyethylenes are thus obtained and characterized by 1H NMR and IR spectroscopy, and MALDI TOF mass spectrometry. These macroRAFT agents may serve as building blocks for the synthesis of block copolymers based on polyolefins and polar segments.
Thio thiocarbonylate‐terminated polyethylene chains are easily prepared in high yield by a two step reaction and analyzed by MALDI‐TOF mass spectrometry. 相似文献
Branched poly(butyl acrylate) was obtained from pulsed‐laser polymerizations carried out in bulk and in solution between −16 and 60 °C. The predominantly short branches are formed by backbiting. The Arrhenius temperature dependence of the backbiting rate is calculated, and the activation energy of this process was found to be remarkably higher than that of propagation. Branching thus increases with temperature leading to broader SEC traces and difficulties in the accurate determination of kp.
Arrhenius plot of kfp2 versus 1/T determined experimentally. 相似文献
Density Functional Theory is used to study the influence of the size of copper clusters modeling the Cu(100) surface, on the electronic properties: ionization potential, electron affinity, electronic chemical potential, and chemical hardness. The model clusters are chosen to have a bilayer structure and range in size from 9 to 20 copper atoms. The chemical hardness being identified as the relaxation energy of the frontier levels when an electron is removed or added to the system, a simple expression is proposed to estimate its value from the eigenenergies of the frontier levels in neutral and partially ionized systems. A detailed comparison of the geometric and electronic structures is made between the model surface copper clusters, real copper clusters, and the actual metal surface; it is seen that the model surface clusters provide an easy extrapolation to the properties of the metal surface. 相似文献
