Figure 2.

Typical ¹H-NMR spectra of block copolymer MPEG-b-PCL.

Notes: ¹H-NMR in CDCl₃ was used, with following results: peak a (δ=4.06 parts per million [ppm], CL repeating unit: –CO–CH₂–CH₂–CH₂–CH₂–CH₂–O–), b (δ=2.32 ppm, CL repeating unit: –CO–CH₂–CH₂–CH₂–CH₂–CH₂–O–), c (δ=1.62–1.67 ppm, CL repeating unit: –CO–CH₂–CH₂–CH₂–CH₂–CH₂–O–), and d (δ=1.38 ppm, CL repeating unit: –CO–CH₂–CH₂–CH₂–CH₂–CH₂–O–). Peak e is the solvent CDCl₃. The peak f at 3.65 ppm was assigned to the (–CH₂–CH₂) protons of the initiator MPEG.

Abbreviations: ¹H-NMR, proton nuclear magnetic resonance; MPEG, methoxy poly(ethylene glycol); MPEG-b-PCL, methoxy poly(ethylene glycol)-b-poly(ε-caprolactone); ppm, parts per million.