Synthesis of well-defined 8-shaped polymers by the combination of RAFT polymerization and click reaction

A series of well-defined 8-shaped polymers have been synthesized by the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and click reaction. Firstly, well-defined, azide-terminated, four-armed star polymers including poly(N,N-dimethylacrylamide) and polystyrene were prepared by RAFT polymerization using pentaerythritoltetrakis(3-(S-(2-azidoethylcarbonoyl)trithiocarbonyl)propanoate) as a chain transfer agent. Then, intramolecular cyclization of the azide-functionalized four-armed precursors was conducted under highly dilution conditions using a bifunctional N,N-bis(2-propargyloxycarbonyl ethyl)-2-hydroxylethyl amine as the linker, affording 8-shaped polymers. FTIR, H-1 NMR, GPC, and MLADI-TOF MS analysis confirmed that the coupling reaction proceeded via the cyclization manner.