Cyclic homo and block copolymers through sequential double click reactions

Well-defined linear α-anthracene-ω-maleimide functionalized polystyrene (l-Anth-PS-MI) and linear α-alkyne-ω-maleimide functionalized poly(tert-butyl acrylate) (l-alkyne-PtBA-MI) homopolymers, and linear α-anthracene-ω-maleimide functionalized PS-b-PtBA (l-Anth-PS-b-PtBA-MI) and linear α-anthracene-ω-maleimide functionalized PS-b-poly(ε-caprolactone) (PCL) (l-Anth-PS-b-PCL-MI) block copolymers were obtained via combination of atom transfer radical polymerization (ATRP)/ring opening polymerization (ROP) and azide-alkyne click reaction strategy. Subsequently, these linear homo and block copolymers were efficiently clicked via Diels-Alder reaction to give their corresponding cyclic homo and block copolymers at reflux temperature of toluene for 48 h under 7-4 x 10⁻⁵ M conditions.