Synthesis Of Ni(?) Catalysts With Salicylaldimino And ?-ketoimino Ligands And Their Catalytic Copolymerization Performace Toward Norbornene

One of the hottest topics for polyolefin materials is to improve the properties of addition-type polynorbornene by the copolymerizaion of norbornene and?-olefins or polar monomers,the catalysts and the catalytic system are the core of the synthesis of polyolefin materials.In this paper,six bis-?salicylaldimino?Ni???complexes with different electronic effecs Ni{?3-R₁??5-R₂?C₆H₂?O?CH[N?naphthyl-CH₂?]}₂?Ni1:R₁=H,R₂=H;Ni2:R₁=H,R₂=CH₃;Ni3:R₁=H,R₂=Br;Ni4:R₁=H,R₂=OCH₃;Ni5:R₁=CH₃,R₂=H;Ni6:R₁=Br,R₂=H?,one bis-?Benzoyltrifluoroacetone-ketoimino?Ni???complex with C-C bridged constrained geometry configuration Ni{C₆H₅C?O?CHC[N?fluorenyl?]CF₃}₂?Ni7?and two bis-?benzocyclohexan-ketoimino?Ni???complexes with rigid structure Ni{C₁₀H₈?O?C[N?Ar?]CH₃}₂?Ni8:Ar=fluorenyl;Ni9:Ar=naphthyl-CH₂?were designed and synthesized,some of the catalysts were characterized by X-ray crystallography.Homo-and copolymerization ofnorbornene?NB?and?-olefin?styrene?St??,polarmonomers?2-butyloxymethylene norbornene?BN?,n-butyl methacrylate?BMA??were carried out by the catalysts in the present of B?C₆F₅?₃ or MAO.The effects of different electron groups and polymerization conditions on the polymerization were investigated,and the microstructures and properties of copolymers were also characterized and analysed.Homopolymerization of norbornene was carried out by Ni1-Ni6/B?C₆F₅?₃,and all the catalysts showed high catalytic activity(10⁶ g_polymer/mol_Ni·h).The experiments showed that the catalysts with electron-withdrawing effect had higher catalytic activity than the catalysts with electron-donating effect in the same substituent position?Ni3>Ni1,Ni2,Ni4;Ni6>Ni1,Ni5?,which illustrated the electron-withdrawing effect was beneficial to the improvement of catalytic activity.The catalyst with electron-withdrawing group?-Br?closer to active center?Ni?had higher catalytic activity than the catalyst with same electron group far from the active center?Ni6>Ni3?.However,it had the opposite conclusion when the substituent groups were electron-donating group?-CH₃??Ni2>Ni5?.Copolymerization of norbornene and 2-butyloxymethylene were carried out by Ni2?Ni3?Ni5/B?C₆F₅?₃,and the catalytic activity of the catalysts are higher than 10⁵ g_polymer/mol_Ni·h.The Ni3had the highest catalytic activity(3.53×10⁵ g_polymer/mol_Ni·h)and the activity order is Ni2>Ni5>Ni3.The reactivity ratio(r_NB=3.12>1,r_St=0.86<1)indicated that norbornene had higher reactivity and the reaction was random copolymerization.The copolymers poly?NB-co-BN?s were characterized by GPC,¹H NMR,¹³C NMR,TGA,DSC,WXRD and FTIR.All the copolymers have high molecular?2.3-4.7×10⁵ g/mol?and narrow molecular weight distributions?PDI:2.08-2.59?,and they were confirmed to be non-crystalline.The copolymers poly?NB-co-BN?s have good solubility and thermal stability?T_d>400 ^oC?.Well defined C-C coupling constrained geometry configuration?CGC?Ni???complexes?Ni7?was synthesized by one-step in situ reaction,and the catalyst was characterized by X-ray crystallography.The catalyst was not be reported until now.The Ni7/B?C₆F₅?₃ catalytic system was used for homo-and copolymerization of norbornene?NB?and Styrene?St?,and the catalyst showed high catalytic activity.The reactivity ratio(r_NB=9.69>1,r_St=0.14<1)indicated that norbornene had higher reactivity and the reaction was random copolymerization.The copolymers poly?NB-co-St?s showed high molecular and narrow molecular weight distributions?M_w/M_n=1.71-2.80?.The copolymers also had good thermal stability?T_d>380.5 ^oC,T_g>156.8?and high light transmittance?>80%?.The catalytic system Ni8,Ni9/MAO were significantly completed the copolymerization of NB and St,and exhibited high catalytic activity(0.94-1.97×10⁵g_polymer mol_Ni^-1 h^-1).The copolymers poly-?NB-co-St?s were non-crystalline and showed high thermal stability?T_d>330 ^oC?.