Polymerization of Norbornene with CoCl₂ and Pyridine Bisimine Cobalt(II) Complexes Activated with MAO

Abstract

Addition polymerization of norbornene was performed with several pyridine bis(imine) cobalt dichloride complexes activated with methylaluminoxane (MAO), first described for ethylene polymerization. For the first time, norbornene was also polymerized with CoCl2 associated to MAO. The influence of several reaction parameters has been investigated. Quite different behavior was observed compared with ethylene polymerization. Moreover, the copolymerization of ethylene and norbornene with these complexes was not possible but led to a mixture of both homopolymers.

Metal catalysts for the vinyl/addition polymerization of norbornene

“…This was shown being due to norbornene polymerization by MAO alone under these conditions. Complex Co-9/MAO gave a monomodal molar mass distribution below 60 • C and bimodal ones above 60 • C. In contrast, Co-8/MAO yielded a bimodal molar mass distribution even at 20 • C [126,127].…”

“…Different polymerization parameters were studied in more detail-NB concentration: For Co-8/MAO, the monomer conversion increased linearly with the norbornene concentration and no difference was observed for the PNB molar masses. Al/Co ratio: With CoCl 2 /MAO a maximal activity was reached for low Al/Co ratios (around 100), whereas the maximum activities for Co-8/MAO and Co-9/MAO were reached for much higher ratios (around 500-2000) [126,127]. For Co-9/MAO and CoCl 2 /MAO the PNB molar masses decreased with increasing Al/Co ratios and the molar mass distribution was always monomodal.…”

“…Different substituents were introduced on the aryl groups of the imine functions in the closely related precatalysts Co-8 to Co-13 in order to modify either the electron density at the metal atom or the steric demand around the catalytic center [126,127]. All precatalysts were activated with MAO and afforded the norbornene polymerization in moderate yields in a range of 4.7 × 10 3 (Co-11/MAO) to 1.3 × 10 4 g polymer /mol Co h (Co-9/MAO).…”

Strained Diphosphines Built upon a Calix[4]arene Skeleton. Synthesis of a Highly Active Norbornene Polymerization Catalyst

“…Zirconocene and titanocene complexes have proven to be efficient for the vinyl polymerization of norbornene. [11][12][13][14][15][16] Many late transition metal catalysts based on cobalt, [17,18] nickel, [19][20][21][22][23][24][25][26][27] or palladium [28][29][30][31][32][33] have also been used successfully.…”

Synthesis, characterization of a novel anilido-iminato cobalt (II) complex and its application for addition polymerization of norbornene

“…Moreover, an increase of the concentration of the monomer norbornene decreases the activity of the polymerization reaction (Table 3, entries 2 and 6). There are several reports on the polymerization of norbornene with cobalt complexes activated with MAO [29][30][31]. Unlike nickel complexes, cobalt complexes have low activities and in some case the ring-opening metathesis polymerization (ROMP) polymer could be observed [30].…”