Synthesis and Characterization of Poly(ethylene glycol)-b-Poly(L-cysteine) Block Copolymer

Amine-terminated mPEG (mPEG-NH₂) was first synthesized by Gabriel method using mPEG-OH as the monomer.Methoxy poly(ethylene glycol)-b-poly(L-cysteine) (mPEG-b-PCys) amphiphilic block copolymers were further synthesized by ring opening copolymerization of S-benzyl L-cysteine N-carboxyanhydride (BCys-NCA) initiated with the amine terminated mPEG and followed by the removal of the protected groups using liquid NH₃/Na.The structures of the polymers were characterized by Nuclear Magnetic Resonance spectroscopy (¹H-NMR) and Fourier Transform Infrared spectroscopy (FT-IR).Results showed that the amphiphilic block copolymers containing active thiol groups were synthesized successfully,and the degree of polymerization was controllable.