Abstract
Copolymerizations of propylene with ω-alkenols (aluminum-protected 5-hexene-1-ol (AH) and 10-undecene-1-ol (AU)) and non-polar analogues (1-hexene and 1-dodecene) were conducted with a rac-[Me2Si(2-Me-4-Ph-Ind)2]ZrCl2 activated by modified methylaluminoxane. The catalytic system showed high activity for each copolymerization, of which value was independent on the comonomer used and decreased with the increase of the comonomer concentration. The comonomer content of the copolymers obtained also decreased with the increase of the comonomer concentration in each copolymer. The evaluation of the monomer reactivity ratios indicates a preference for the propylene insertion regardless of the last inserted monomer unit in growing polymer chain in all the copolymerizations. The relative reactivity of ω-alkenols was however significantly lower than that of non-polar analogues. These results suggested that the aluminum protection of polar monomer do not affect the activity of copolymerization but significantly decrease the comonomer reactivity.
Highlights
Polyolefins having polar functionalized side groups have a greater demand due to their unique properties such as adhesion, toughness, print/paintability, miscibility and rheological properties [1,2]
The direct copolymerization of olefin with polar functional monomer is an efficient method for the synthesis of functionalized polyolefins with control of the amount of functional group and their distribution in the polymer backbone
Late transition metal catalysts are widely applied in the area of the direct copolymerization of functional groups with ethylene, since they are more tolerant to the functional groups and applicable to copolymerize the polar functional monomers [5,6]
Summary
Polyolefins having polar functionalized side groups have a greater demand due to their unique properties such as adhesion, toughness, print/paintability, miscibility and rheological properties [1,2]. The direct copolymerization of olefin with polar functional monomer is an efficient method for the synthesis of functionalized polyolefins with control of the amount of functional group and their distribution in the polymer backbone. Several new early transition catalysts have been developed to copolymerize ethylene and polar comonomers with high activity and good contents of comonomer. Sun and co-workers reported that titanium complexes bearing [ONX] tridentate ligands are highly active in the copolymerization of ethylene with various aluminum-protected polar comonomers with highest activity of 130,000 kg-polymer mol-Ti1 ̈ h1 and a comonomer content of 3.3 mol % [24,25]. Ziegler-Natta and metallocene catalysts can be applicable to functional group protection method, the activity of copolymerization with propylene is much lower than those with ethylene, especially at higher concentration of comonomer [9,26]. The comparison results of copolymerization indicate that protecting group is not the main reason for the decrease of the copolymerization activity but can dramatically influence the comonomer reactivity
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