The composition and the microstructures of isoprene-methyl methacrylate copolymers havebeen quantitatively studied by 250 MHz 1H-NMR spectra. Applying two lanthanide shiftreagents, by examining the separation of reson...The composition and the microstructures of isoprene-methyl methacrylate copolymers havebeen quantitatively studied by 250 MHz 1H-NMR spectra. Applying two lanthanide shiftreagents, by examining the separation of resonance peaks of the 1,4-isoprene olefin proton,I-centred triad distributions, and even I-cectred pentad fractions are measured. It is con-firmed that there is a penultimate of effect in this free radical copolymerization and the reac-tivity ratios established corresponding to Second-order Markov chain model are r11=0.48,rMI=0.86, rMM=0.51 and rIM=0.43, respectively. The observed I-centred pentad fraetions andM-centred triad distributions agree with the above results.展开更多
文摘The composition and the microstructures of isoprene-methyl methacrylate copolymers havebeen quantitatively studied by 250 MHz 1H-NMR spectra. Applying two lanthanide shiftreagents, by examining the separation of resonance peaks of the 1,4-isoprene olefin proton,I-centred triad distributions, and even I-cectred pentad fractions are measured. It is con-firmed that there is a penultimate of effect in this free radical copolymerization and the reac-tivity ratios established corresponding to Second-order Markov chain model are r11=0.48,rMI=0.86, rMM=0.51 and rIM=0.43, respectively. The observed I-centred pentad fraetions andM-centred triad distributions agree with the above results.
