Poly(N-vinylcarbazole) star polymers and amphiphilic star block copolymers by xanthate-mediated controlled radical polymerization

Four-arm poly(N-vinylcarbazole), poly(NVC), stars were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization/macromolecular design via interchange of xanthates (MADIX) using three different xanthate-type tetrafunctional chain transfer agents (CTAs). Two Z-designed CTAs having different R (leaving) groups, in which the Z (stabilizing) groups are linked to the core, and one R-designed CTA were compared. The R-group approach was found to be the most efficient for the controlled synthesis of four-arm poly(NVC) stars having a low polydispersity and controlled molecular weights. Amphiphilic star block copolymers were synthesized by the polymerization of NVC using the poly(acrylic acid) star, which was prepared from the R-designed tetrafunctional CTA. The characteristic assembled structures and optical properties of the amphiphilic star block copolymers in selective solvents were investigated by dynamic light scattering (DLS), UV-vis, and fluorescence spectroscopic methods.