Glasses‐shaped triblock copolymer prepared by combination of atom transfer radical polymerization and ring opening polymerization

A glasses‐shaped triblock copolymer of poly(ε‐caprolactone)‐b‐polystyrene‐b‐poly(ε‐caprolactone) (PCL‐b‐PS‐b‐PCL) is prepared by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). Polystyrene (PS) star polymers are prepared via ATRP using a tetra‐functional initiator, followed by azidation to yield azide end‐functionalized star polymers. An alkyne‐functionalized coupling agent, 2,2‐bis[(2‐propyn‐1‐yloxy)methyl]‐1‐propanol is employed to produce hydroxy 8‐shaped PS via copper(I)‐catalyzed alkyne‐azide cycloaddition. Herein, hydroxy 8‐shaped PS with high purity is obtained through preparative size exclusion chromatography (Prep SEC) and high‐performance liquid chromatography, followed by the characterizations using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS), size exclusion chromatography (SEC), infrared, and proton nuclear magnetic resonance (1H NMR) spectroscopy. The hydroxy groups of the 8‐shaped PS are utilized as initiators for the ROP of ε‐caprolactone to obtain linear chains attached to the 8‐shaped architecture. After SEC fractionation, the glasses‐shaped triblock copolymer is characterized using 1H NMR and SEC. This unprecedented topology possesses two free chain‐ends and two cycles; thus, both the properties of linear and cyclic polymers may be expected to be observed.