writer：Yang Jianga, Shihui Li* , Dongmei Cui*
keywords：Ethyl vinyl ether,Rare-earth metal, Cationic polymerization, Ultra-high molecular weight, High activity
source：期刊
specific source：Polymer 226 (2021) 123790
Issue time：2021年

Ethyl vinyl ether (EVE) polymerizations by rare-earth metal complexes were studied. The metallocene complexes1–3 activated by organoborate displayed extremely high catalytic activities (≤1.50×10⁶ g mol^-1h^-1) for EVEpolymerization at 25 ^?C. The non-metallocene complexes 4–6 were nearly inert under the same conditions. Theresultant molecular weights produced by 1/[Ph₃C][B(C₆F₅₎₄] increased from 2.98 ×10⁴ to 19.3 ×10⁴ g mol^-1 with the temperature declining from 0 to 45 ^?C and the addition of 10 equivalents of AlⁱBu₃ to the binary system 1/[Ph3C][B(C6F5)4] resulted in the higher molecular weight product (32.5 ×10⁴ g mol^-1) at .45^?C.With the molar ratio of EVE-to-1 increased from 2000:1 to 10000:1, the resultant molecular weight reached107.3 ×10⁴ g mol^-1 but the catalytic activity dropped dramatically from 7.60 ×10⁵ to 0.57 ×10⁵ g mol _Sc^-1 h^-1.The dicationic species formed by the reaction of 1 with 2 equivalents of [Ph₃C][B(C₆F₅)₄] displayed high catalytic activity for EVE

polymerization and gave high molecular weight product in the presence of AlⁱBu₃.