Facile Synthesis of Helical Rod-Coil Block Polymers by the Combination of ATRP and Pd(II)-Initiated Isocyanides Polymerizations

A bifunctional initiator containing propargyl bromoisobutyrate and alkyne-Pd(II) (PBB-Pd(II)) is designed and synthesized. The propargyl bromoisobutyrate unit of PBB-Pd(II) can initiate the atom transfer radical polymerization (ATRP) of vinyl monomers, while the Pd(II) complex can initiate the polymerization of phenyl isocyanides. Both the ATRP and Pd(II)-mediated isocyanide polymerization are proceeded in living/controlled manner. Thus, combining the two living polymerizations, a series of well-defined block copolymers bearing rod poly(phenyl isocyanide)s and coil poly(acrylate) segments can be facilely prepared in high yield with tunable composition, controlled molar masses (M(n)s), and narrow molar mass distributions (M-w/M(n)s). What is more, benefiting from this synthetic strategy, well-defined core cross-linked star polymers are readily synthesized. Optically active block copolymers and star polymers can be facilely obtained by using chiral isocyanide monomers due to the formation of predominated one-handed helix. The chiral star polymers show excellent enantioselective recognition ability in enantioselective crystallization of racemic compounds.