作者：Zhang, ZC; Cui, DM; Wang, BL; Liu, B; Yang, Y
关键字：Diene polymerization; Metallocene; Rare-earth metals; Specific polymerization; Ziegler-Natta
论文来源：期刊
具体来源：Diene polymerization; Metallocene; Rare-earth metals; Specific polymerization; Ziegler-Natta
发表时间：2011年
This chapter surveys the publications
except patents related to cis-1,4-, trans-1,4-, 3,4-regio-, and
stereoselective polymerizations of 1,3-conjugateddienes with rare-earth metal-based
catalytic systems during the past decade from 1999 to 2009. The concerned
catalyst systems are classified into the conventional Ziegler-Natta catalysts,
the modified Ziegler-Natta catalysts, and the single-site cationic systems
composed of lanthanocene and noncyclopentadienyl precursors,
respectively. For the conventional Ziegler-Natta catalysts of the
most promising industry applicable recipe, the multicomponents based on
lanthanide carboxylate or phosphate or alkoxide precursors, research works concern
mainly about optimizing the catalyst preparation and polymerization techniques.
Special emphases are put on the factors that influence the catalyst
homogeneority, catalytic activity and efficiency, as well as cis-1,4-selectivity.
Meanwhile, tailor-made lanthanide aryloxide and amide complexes are designed
and fully characterized to mimic the conventional Ziegler-Natta catalysts,
anticipated to elucidate the key processes, alkylation and cationization, for
generating the active species. Regarding to the single-site catalytic systems
generally comprising well-defined complexes containing lanthanide-carbon bonds,
investigations cover their versatile catalytic activity and efficiency, and the
distinguished regio- and stereoselectivity for bothpolymerization of dienes and
copolymerization of dienes with alkenes. The correlation
between the sterics and electronics of ligands and the molecular
structures of the complexes and their catalytic performances are
highlighted. The isolation of the probable active species in thesepolymerization processes
from the stoichiometric reactions of the precursors with activators
will be presented.112:3110-3118, 2009