Multiarm star triblock terpolymers via sequential double click reactions

Multiarm star triblock terpolymers were obtained by using two different click reactions sequentially: Cu(I) catalyzed azide-alkyne and Diels-Alder. The synthetic strategy is described as follows: (poly(methyl methacrylate)) _n-(polystyrene)_m-poly(divinyl benzene)) ((PMMA) _n-(PS)_m-polyDVB) multiarm star diblock copolymer was first obtained from an azide-alkyne click reaction of (alkyne-PS)_m-polyDVB multiarm star polymer with α-anthracene- ω-azide PMMA (anth-PMMA-N₃), followed by a Diels-Alder click reaction of the anthracene groups at the star periphery with α-maleimide poly (tert-butyl acrylate) (PtBA-MI) or α-maleimide poly(ethylene glycol) (PEG-MI) leading to target (PtBA)_k- (PMMA)_n-(PS)_m-polyDVB and (PEG)_p-(PMMA)_n-(PS)_m-polyDVB multiarm star triblock terpolymers. The hydrodynamic diameter of individual multiarm star triblock terpolymers were measured by dynamic light scattering (DLS) to be ∼24-27 nm in consistent with the atomic force microscopy (AFM) images on silicon substrates.