Wang Kaiti, Wang Jiabao, Li Yanguo, Pan Li, Li Yuesheng
Tianjin Key Lab of Composite & Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China.
Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
Polymers (Basel). 2017 Aug 11;9(8):353. doi: 10.3390/polym9080353.
Non-metallocene oxovanadium(V) complexes bearing either [ONNO]-type amine pyridine bis(phenolate) ligands or [ONN]-type amine pyridine phenolate ligands were employed as efficient catalysts to copolymerize ethylene with several unsymmetrical norbornene-containing dienes, such as 5-vinyl-2-norbornene (VNB), 5-ethylidene-2-norbornene (ENB) or dicyclopentadiene (DCPD), producing copolymers with high comonomer incorporations (VNB: 33.0 mol %; ENB: 30.4 mol %; DCPD: 31.6 mol %, respectively) and high molecular weight (VNB: 86.4 kDa; ENB: 256 kDa; DCPD: 86.4 kDa, respectively). The enchainment of the dienes was proven to be exclusive of vinyl-addition via the C=C double bond of the norbornene ring while the other double bond was retained near the backbone without crosslinking. During the copolymerization of ethylene with ENB, a positive 'comonomer effect' was observed. The catalytic activities of the catalysts as well as the molecular weights and comonomer incorporations of the resultant copolymers could be tuned within a wide range by varying the structures of the catalysts and copolymerization conditions. The [ONN]-type oxovanadium(V) complexes showed higher catalytic activities than those of [ONNO]-type oxovanadium(V) complexes, irrespective of the structure of the dienes. In addition, the dominant chain transfer pathway of the non-metallocene oxovanadium(V) catalytic system promoted copolymerization was proven to be transfer to aluminum compounds.
带有[ONNO]型胺吡啶双（酚盐）配体或[ONN]型胺吡啶酚盐配体的非茂氧钒（V）配合物被用作高效催化剂，用于使乙烯与几种含降冰片烯的不对称二烯共聚，如5-乙烯基-2-降冰片烯（VNB）、5-亚乙基-2-降冰片烯（ENB）或二环戊二烯（DCPD），得到具有高共聚单体掺入量（分别为VNB：33.0 mol%；ENB：30.4 mol%；DCPD：31.6 mol%）和高分子量（分别为VNB：86.4 kDa；ENB：256 kDa；DCPD：86.4 kDa）的共聚物。已证明二烯的插入是通过降冰片烯环的C=C双键进行的乙烯基加成，而另一个双键保留在主链附近且无交联。在乙烯与ENB的共聚过程中，观察到了正的“共聚单体效应”。通过改变催化剂结构和共聚条件，催化剂的催化活性以及所得共聚物的分子量和共聚单体掺入量可在很宽范围内进行调节。无论二烯的结构如何，[ONN]型氧钒（V）配合物均显示出比[ONNO]型氧钒（V）配合物更高的催化活性。此外，已证明非茂氧钒（V）催化体系促进共聚的主要链转移途径是转移至铝化合物。
