Styrene polymerization with nickel complexes/methylaluminoxane catalytic system

Abstract

Polymerization of styrene using β-diketiminate nickel (II) bromide complexes CH{C(R)NAr} 2 NiBr (R = CH 3 , Ar = 2,6-i Pr 2 C 6 H 3 , 1; R = CH 3 , Ar = 2,6-Me 2 C 6 H 3 , 2; R = CF 3 , Ar = 2,6-i Pr 2 C 6 H 3 , 3; R = CF 3 , Ar = 2,6-Me 2 C 6 H 3 , 4) in the presence of methylaluminoxane was studied. Compound 3 is the most active styrene polymerization catalyst of all the nickel complexes tested. The activity of these catalysts increases with increases in steric bulk of the substituents on the aryl rings. The electronic nature of the ligand backbone also affects the activity. Weight-average molecular weight of the prepared polystyrene ranges from 21 000 to 72 000, with polydispersity indexes of 1.95-2.78. The microstructure of the obtained products is atactic polystyrenes from NMR analyses.

Tuning steric and electronic effects in transition-metal β-diketiminate complexes

“…L R,R’ NiBr, L R,R’ NiPh(PPh 3 ) and L Me,R’ Ni(alkyl) (R = CF 3 , Me; R’ = i Pr, Me) were reported to be active catalysts for ethylene, 102, 103 styrene, 104 norbornene 105, 106 polymerization and their copolymerization. 107, 108 The polymer yield was significantly higher with more hindered ligand systems.…”

Novel cycloaurated gold(III) complexes and their effects on styrene polymerization

“…Chemical shifts between 6.39 and 7.42 ppm are aromatic hydrogen signals. The 1.72-2.43 ppm are methyne hydrogen signals and chemical shifts between 0.97 and 1.76 ppm are methylene hydrogen signals in polystyrene [21]. Figure 3 shows the comparison 13 C-NMR spectrums of polystyrene in CDCl 3 solution with catalyst and without catalyst.…”

Polymerization of styrene using pyrazolylimine nickel (II)/methylaluminoxane catalytic systems

“…End group analysis of the polymer confirmed a coordination mechanism, and atactic PS was obtained. Moreover, styrene polymerization with using β‐diketiminate nickel (II) complexes with activation of MAO was reported and the resulting PS also was atactic polymer 27…”