Characterization of poly(L-lactic acid)-polyethylene glycol copolymers synthesized by melt copolymerization

Prepolymers were prepared through a dehydration process from L-lactic acid. Poly(L-lactic acid)-polyethylene glycol(PLLA-PEGs) copolymers were prepared by the direct melt polymerization of prepolymer and polyethylene glycol using TSA/SnCl₂/Sn(Oct)₂ as catalyst. FT-IR and ¹H-NMR spectra show that the structures of copolymers are mainly PLLA-PEGs. DSC results show that the glass transition temperature, melting point and crystallinity of the copolymer are lower than those of neat PLLA. The optical rotation of L-lactic acid decreases during the polymerization. The rheological analysis shows that the tenacity of copolymer increases.