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Controlled Polymerization of Isoprene with Chromium‐Based Metal‐Organic Framework Catalysts: Switching from Cyclic to cis ‐1,4‐Selectivity Depending on Activator
Author(s) -
Gao Fei,
Zhang Li,
Yu Chao,
Yan Xinwen,
Zhang Shaowen,
Li Xiaofang
Publication year - 2018
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201800002
Subject(s) - isoprene , cationic polymerization , polymerization , catalysis , selectivity , chromium , chemistry , polymer chemistry , metal organic framework , materials science , chemical engineering , copolymer , organic chemistry , polymer , adsorption , engineering
Abstract Chromium‐based metal‐organic framework (MOF) Cr‐MIL‐100/101 activated by activator and aluminum trialkyl compound serve as unique, highly efficient heterogeneous single‐site catalysts for the controlled polymerization of isoprene, which not only exhibit quasi‐living nature in isoprene polymerization but also unprecedentedly switch from cyclic to cis ‐1,4‐selectivity depending on the activator used to yield low molecular weight cyclic PIPs or extremely high molecular weight cis ‐1,4‐PIPs. Such heterogeneous Cr‐MOF catalysts can be recycled approximately five times. Based on nitrogen sorption isotherm tests and powder X‐ray diffraction, a cationic mechanism is suggested, in which the polymerization takes place inside the open nanochannels of MOF catalysts and the space confinement effect of narrow open nanochannels originated from the coordination of PhNMe 2 from activator [PhNHMe 2 ][B(C 6 F 5 ) 4 ] with the multiple metal centers of MOF catalysts might give a rational explanation for such controlled adjustment on the PIP's structure and properties.