ABC-type hetero-arm star terpolymers through "click" chemistry

Hetero-arm star ABC-type terpolymers, poly(methyl methacrylate)- polystyrene-poly(tert-butyl acrylate) (PMMA-PS-RBA) and PMMA-PS-poly(ethylene glycol) (PEG), were prepared by using "Click" chemistry strategy. For this, first, PMMA-b-PS with alkyne functional group at the junction point was obtained from successive atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMP) routes. Furthermore, PtBA obtained from ATRP of tBA and commercially available monohydroxyl PEG were efficiently converted to the azide end-functionalized polymers. As a second step, the alkyne and azide functional polymers were reacted to give the hetero-arm star polymers in the presence of CuBr/N,N,N′,N″,N″- pentamethyldiethylenetriamine (PMDETA) in DMF at room temperature for 24 h. The hetero-arm star polymers were characterized by ¹H NMR, GPC, and DSC.