One-pot synthesis of star-block copolymers using double click reactions

3-Arm star-block copolymers, (polystyrene-b-poly(methyl methacrylate)) ₃, (PS-b-PMMA)₃, and (polystyrene-b-poly(ethylene glycol))₃, (PS-b-PEG)₃, are prepared using double-click reactions: Huisgen and Diels-Alder, with a one-pot technique. PS and PMMA blocks with x-anthracene-ω-azide- and x-maleimide-end-groups, respectively, are achieved using suitable initiators in ATRP of styrene and MMA, respectively. However, PEG obtained from a commercial source is reacted with 3-acetyl-N-(2-hydroxyethyl)-7-oxabicyclor2.2.1.]hept-5-ene-2-carboxamide (7) to give furan-protected maleimide-end-functionalized PEG. Finally, PS/PMMA and PS/PEG blocks are linked efficiently with trialkyne functional linking agent 1,1,1-tris[4-(2-propynyloxy)-phenyl]-ethane 2 in the presence of CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) at 120°C for 48 h to give two samples of 3-arm star-block copolymers. The results of the peak splitting using a Gaussian deconvolution of the obtained GPC traces for (PS-b-PMMA)₃ and (PS-b-PEG)₃ displayed that the yields of target 3-arm star-block copolymers were found to be 88 and 82%, respectively.