Synthesis of ethylene/1-octene copolymers with controlled block structures by semibatch living copolymerization


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A kinetic model was developed for the living copolymerization of ethylene/1-octene using the fluorinated FI-Ti catalyst system, bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] TiCl2/dried methylaluminoxane is presented. The model was first validated by batch polymerization experiments. Kinetic parameters were estimated from the model correlations with online ethylene consumption rates and end-of-batch copolymer molecular weight. The model was then used to calculate the microstructural properties of ethylene/1-octene copolymers with controlled composition profiles (uniform, diblock, and step triblock), which were synthesized using sequential comonomer feeding policies in semibatch copolymerization. The synthesized block copolymers had the exact composition distributions and molecular weights as the model simulated. It was demonstrated that the polymer chain microstructure in the living copolymerization of olefins could be precisely regulated by using semibatch comonomer feeding policies. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4686–4695, 2013