Water-soluble poly(N-vinyl-1,2,4-triazole) star and amphiphilic star block copolymers by RAFT polymerization

Water-soluble star polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of N-vinyl-1,2,4-triazole (NVTri), which is a non-conjugated N-vinyl monomer having an aromatic heterocycle. Four-arm poly(NVTri)s having low polydispersities and controlled molecular weights were obtained using a xanthate-type tetrafunctional chain transfer agent (CTA). Amphiphilic star block copolymers having inner water-soluble segments connected to the core were synthesized by RAFT polymerization of N-vinylcarbazole (NVC) using poly(NVTri) star as a macro-CTA. In contrast, RAFT polymerization of NVTri using poly(NVC) star afforded star block copolymers with block arms consisting of inner optoelectronic poly(NVC) segment and outer hydrophilic poly(NVTri) segment. Assembled structures of these amphiphilic star block copolymers formed in selective solvents and characteristic optoelectronic properties were evaluated by dynamic light scattering (DLS), UV-vis, and fluorescence spectroscopic methods.