Vinyl polymerization of norbornene with dinuclear diimine nickel dichloride/MAO

Abstract

ABSTRACT:Vinyl-addition polymerization of norbornene was accomplished by two novel dinuclear diimine nickel dichloride complexes in combination with methylaluminoxane (MAO). The activities were moderate. The catalyst structure, Al/Ni molar ratio, solvents, and polymerization temperature all affected the catalytic activities. The obtained polynorbornenes were characterized by 1 H-NMR, 13 C-NMR, FTIR, DSC, WAXD, and intrinsic viscosity measurements. The vinyl-addition polymers were amorphous but with a short-range order and high packing density. The polynorbornenes showed glass transition temperatures (T g ) above 240°C and decomposed above 400°C. The catalyst structure and polymerization conditions have effects on the molecular weight and the microstructure of the polymers. The nickel complex with bulkier substituents in the ligand produced polynorbornene with a higher packing density and higher regularity and, therefore, with higher T g .

Metal catalysts for the vinyl/addition polymerization of norbornene

“…Furthermore, in the more polar solvent mixture toluene/dichloromethane higher activities were generated than in pure toluene for Ni-37/MAO. For a temperature of 0 • C the optimal activity was observed and an increase in temperature lowered the activity [146].…”

Synthesis, characterization and olefin polymerization of the nickel catalysts supported by [N,S] ligands

“…The reason may be that norbornene is a sterically encumbered monomer, and it need more sterically open nature [38,48]. Although these Ni complexes 2a-2b exhibited a little lower activity than the nickel complexes bearing N-substituents imidazole-2-thione ligands (1.36 Â 10 8 gPNBmol À1 Nih À1 ) [38], they are as highly active as nickel complexes bearing [N,O] and [N,N] ligands [21][22][25][26][27][29][30][31][32] and show a very higher activity polymerization than other transition metal catalysts [12][13][14][15][16][17][18][19][20][23][24]28,[33][34][35][36][37]. The amount of the co-catalyst MAO affects obviously the activity and molecular weight of the PNB obtained by the complex 2a (Entry 3-5, Table 2).…”

“…Up to now, catalytic systems based on titanium [12], zirconium [13], cobalt [14][15][16][17], chromium [14,[18][19], nickel [20][21][22][23][24][25][26][27][28][29][30][31][32][33], palladium [33][34][35] and copper [31][32][36][37] have been mainly reported for the addition-polymerization of NB. Especially, the nickel complexes bearing [N,O] and [N,N] ligands using for norbornene polymerization exhibited high activity [21][22][25][26][27][29][30][31][32]. Recently, our group found that nickel complexes bearing soft atom donor ligands N-substituents imidazole-2-thione and imidazole-2-selone activated with MAO exhibited very high activity for norbornene polymerization [38].…”

Synthesis, structure and norbornene polymerization behavior of nickel complexes bearing two β-ketoiminato chelate ligands

“…The vinylic polymerization of norbornene, yielding a 2,3-connected, rotationally strongly constrained vinyl-type polynorbornene, has been considerably attracted because of the polymer having unique physical properties, such as high glass transition temperature, optical transparency, and low birefringence [5,6]. The vinyl-type polybnorbornene can be prepared using metal complexes based on nickel [7][8][9][10][11][12][13][14][15][16], chromium [17], titanium [18][19][20][21][22][23][24], zirconium [25][26][27][28], iron [29], cobalt [30][31][32], and palladium [16,[33][34][35][36][37][38][39][40][41][42] as catalyst. Zirconocenes and cationic palladium complexes are two types of important catalysts for the vinylic polymerization of norbornene.…”