In a nitrogen-filled glove box (oxygen and water content lower than 0.1 ppm), solutions of diphenylphosphate (DPP, 17.0 mg, 1 eq) in dry toluene (2.5 mL) and dual-head CTA (17.0 mg, 1 eq) in dry toluene (1 mL) were added to ε-caprolactone dry toluene solution (543.3 mg, 70 eq in 1.5 mL). After stirring for 6 h at room temperature, the solution was removed from the glove box, precipitated three times into cold diethyl ether dropwise, and collected by centrifugation. PCL 45 (100.0 mg, 1 eq), DMA (736.3 mg, 400 eq), and AIBN (0.3 mg, 0.1 eq) were dissolved in 1,4-dioxane (1 mL) and placed in an ampule. The solution was then freeze-pump-thawed three times and heated for 2 h at 70 • C. The reaction was quenched by immersion of the ampule in liquid nitrogen and the polymer was precipitated in ice-cold diethyl ether three times before being dried under vacuum and analyzed. SEC (chloroform, PMMA standard):