Controlled Pd(O)/f-Bu_3P-Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with PhPd(t-Bu_3P)l or Pd-2(dba)_3/f-Bu_3P/Arl as the Initiator

摘要

Controlled Pd(0)/t-Bu_3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with an ArPd(f-Bu_3P)l complex as the initiator are described. ArPd(f-Bu_3P)I complexes, either prepurified or generated in situ from Pd_2(dba)_3/f-Bu_3P/ArI (dba = dibenzylideneacetone) without separation/purification, were found to be efficient initiators in general for the controlled Suzuki cross-coupling polymerization, with narrow polydispersity indexes (PDIs) of 1.13-1.35 being observed. The Pd_2(dba)_3/t-Bu_3P/P-BrC_6H_4I combination was identified as a highly robust initiator system, with PDIs of <1.20 in general and as low as 1.13 being obtained. Higher number-average molecular weights (M_n) were achieved without a significant increase in the PDI (from 1.14 for a polymer with a M_n = 9500 to 1.20 for a polymer with M_n = 31 400) by using a smaller amount of the Pd_2(dba)_3/f-Bu_3P/p-BrC_6H_4I initiator in the polymerization.