Conference Paper Nickel(0)-Catalyzed Polycondensation of Silafluorene: Control over Molecular Weight and Polymer Growth Mechanism

田邊, 真  ,  Tanabe, Makoto  ,  岩瀬, 駿介  ,  Iwase, Shunsuke  ,  小坂田, 耕太郎  ,  OSAKADA, KOHTARO

35 ( No. 15 )  , p.2557 , 2016-06
The catalytic polymerization of silafluorenes with [Ni(dmpe)2] (dmpe = 1,2-bis(dimethylphosphino)ethane) afforded 2,7-dibutoxy-9H-9-silafluorene polymers with a narrow polydispersity (Mw/Mn < 1.1). In an open vessel, the polymerization ceased shortly after complete consumption of the monomer, but transfer of the reaction mixture into a closed system resumed the polymer growth. Polymerization in a closed system with occasional removal of the evolved H2 furnished soluble polymers with a maximum molecular weight of Mn = 3860. Treatment of a 2,7-dibutoxy-9H-9-silafluorene tetramer with [Ni(dmpe)2] resulted in the initial formation of a mixture of monomers and trimers, which subsequently transformed into oligomers (Si1–Si9). This polymerization involves a preferential dehydrogenative condensation between the monomer and an oligomer relative to that between oligomers, while the presence of H2 regenerates the monomer after its consumption and thus promotes further polymer growth.

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