Coordination Copolymerization of Ethylene with Vinyl Pentamethyldisiloxane
Owing to the unique"chain walking"mechanism and tolerance of polar groups,post-transition metal catalysts can be utilized for the copolymerization of α-olefin with polar monomers,resulting in the production of high-quality functional polyolefins with desired structure and properties.In this study,under the activation of ethylaluminum sesquichloride,the coordination copolymerization of ethylene with vinyl pentamethyldisiloxane(VPMDSO)using α-diimine nickel(Ⅱ)complexes(C1—C6)as catalysts was performed.The effects of VPMDSO monomer concentration,catalyst dosage,Al/Ni molar ratio,ethylene pressure,polymerization time,solvent,and catalyst structure on copolymerization were examined,and the optimal polymerization conditions were obtained.The microstructures,silicon content,thermal stability and surface energy of the copolymer were characterized by proton nuclear magnetic resonance(1H NMR),Fourier transform infrared(FTIR)spectroscopy,gel permeation chromato-graphy(GPC)analysis,thermogravimetry analysis(TGA)and contact angle measurement.The results show that the copolymerization catalytic activity of α-diimide nickel(Ⅱ)complex could reach to 1.26×106 g·mol-1Ni·h-1 while the silicon content range between 0.25％to 0.87％.Compared to polyethylene,the surface energy of the copolymer films decreased and the hydrophobicity increased.
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