A Novel Branched–Hyperbranched Block Polyolefin Produced via Chain Shuttling Polymerization from Ethylene Alone

A novel branched-hyperbranched polyethylene was synthesized via chain walking and chain shuttling polymerization by one step. In polymerization, {2,6- i Pr2-C6H3N˭C(CH3)-(CH3)C˭N- i Pr2-C6H2}NiBr2(CatA) and {2,6-Me2-C6H3N˭C(CH3)-(CH3)C˭N-Me2-C6H2}NiBr2(CatB) was adopted to yield branched and hyperbranched segments via chain walking polymerization at one ethylene atm and 20°C, respectively. Then the chain transfer agent(ZnEt2) facilitated chain transfer between two active metal centers to accomplish chain shuttling polymerization of ethylene. This strategy stands out from “living”/controlled polymerization and coupling block polymers techniques for just using ethylene as monomer, carrying out under moderate polymerization and obtaining the resultant polymer with novel microstructure.