Unprecedented 3,4-Isoprene and cis-1,4-Butadiene Copolymers with Controlled Sequence Distribution by Single Yttrium Cationic Species
writer：Liu, B,Wang, XB, Pan, YP,Lin, F,Wu, CJ,Qu, JP,Luo, Y,Cui, DM
keywords：chain-shuttling polymerization; earth-metal precursors; isoprene polymerization; 1,3-diene polymerization; structural chemistry; molecular-structure; conjugated dienes; c-13 nmr; complexes; butadiene
source：期刊
specific source：http://pubs.acs.org/doi/abs/10.1021/ma5019654
Issue time：2014年
Precisely controlling the stereochemistry of a copolymerization by single catalyst, and achieving copolymers with predicted sequences, is a challenging project in organometallic and macromolecular sciences. This article reports that the copolymerization of isoprene and butadiene with the 3,4- and cis-1,4 different regioselectivities has been accessed through employing a pyridylmethylene functionalized fluorenyl ligated yttrium cationic species. The thus unprecedented regularity combination is attributed mainly to the backbiting interaction of the penultimate unit of the polymer chain to the active central metal ion according to the DFT calculation. Moreover, the compositions can be adjusted by regulating the monomer feed ratio according to the copolymerization kinetics study.
