Homo‐ and copolymerization of norbornene with styrene catalyzed by a series of copper(II) complexes in the presence of methylaluminoxane

Abstract

Vinyl-type polymerization of norbornene as well as random copolymerization of norbornene with styrene was studied using a series of copper complexes-MAO. The precatalysts used here are copper complexes with β-ketoamine ligands based on pyrazolone derivatives and the molecular structure of complex 4 was determined using X-ray analysis. All of these catalyst systems are moderately active for the vinyl-type polymerization of norbornene and random copolymerization of norbornene with styrene. The random copolymers obtained suggest that only one type of active species is present. Gel permeation chromatography (GPC) and NMR indicate that the copolymers are 'true' copolymers. The copolymerization reactivity ratios (r NBE = 20.11 and r Sty = 0.035) indicate a much higher reactivity of norbornene, which suggests a coordination polymerization mechanism. The solubility and processability of the copolymers are improved relative to polynorbornene and the thermostability of the copolymers is improved relative to polystyrene.

Copolymerization of styrene and norbornene with β‐diketiminato nickel/methylaluminoxane catalytic system

“…The trend corresponds to the behavior in the styrene or norbornene homopolymerization . A decreased M w value of the copolymers obtained with an increase in the reaction temperature is ascribed to the fast chain transfer or termination at high temperature . Besides, styrene content in the copolymers increases with the increase in the polymerization temperature; it seems that the high temperature is favorable for producing S‐N copolymers with high styrene content in copolymer.…”

“…Figure illustrates the 13 C NMR spectrum of S‐N copolymer obtained from 1/MAO with styrene incorporation of 41.7%. According to the reported assignment of the S‐N copolymer, the signals of each chemical shift region were assigned as follows: 146 ppm for C 1 , 127.3 ppm for C 2 , 127.9 ppm for C 3 , 125.5 for C 4 , 41.6–44.2 and 40.5 ppm for C 5 and C 6 of the styrene segment; 47.4–52.4 ppm for C 3 , 38.6–39.7 ppm for C 2 , 35–37.4 ppm for C 4 and 29.8–31.6 ppm for C 1 of the norbornene segment. The chemical shifts of the carbon signals of styrene and norbornene segment are not completely consistent with that in the homopolymers of styrene and norbornene because their copolymerization leads to different tacticity of the copolymer and the homopolymer .…”

“…The polymer yields were generally low. Copolymerization of norbornene and styrene were also carried out with copper bis(β‐ketoamine) complexes in the presence of MAO, and random styrene–norbornene copolymers were obtained, but polymer yields were very low. Other kinds of cyclic olefins, such as tetracyclododecene and 2‐phenyl‐2‐norbornene, have also been used for the synthesis of cyclic olefin copolymers to modify their physical properties.…”

Metal catalysts for the vinyl/addition polymerization of norbornene

“…For the complexes Cu-6 to Cu-9 with N,O-chelatingˇ-ketoiminato ligands in combination with MAO both steric and electronic effects contribute to the catalytic activities which were in the order of Cu-7 > Cu-9 > Cu-8 > Cu-6 and between 1.31 × 10 4 and 6.35 × 10 4 g polymer /mol Cu h [203,204]. The sequence of decreasing activity correlated with the decrease in the bulkiness of the iminato-R-substituent.…”

“…The system Cu-9/MAO with its electron-withdrawing p-nitrophenyl group and more electrondeficient Cu(II) center gave a similar high activity than Cu-7/MAO [203]. The catalytic system Cu-73/MAO showed the lowest activity among this group of ␤-ketoiminato Cu(II) complexes [204].…”