Synthesis and Preparation of Micelles of Poly(carbonate-co-ethylene glycol) Block Copolymers with End Group Folate

Biodegradable copolymers of poly(5,5-dimethyl-1,3-dioxan-2-one)-b-methoxy poly(ethylene glycol) (DMP) were synthesized by the ring-opening polymerization of 5,5-dimethyl-1,3-dioxan-2-one (DTC) in bulk with methoxy poly(ethylene glycol) (mPEG) as initiator in the absence of catalyst. Then biodegradable amphiphilic copolymers with end group folate (FA-DMP) were obtained by reaction of DMP with folate(FA). The resulting copolymers were characterized by Fourier Transform Infrared Spectra (FT-IR), 1H-Nuclear Magnetic Resonance (1H-NMR), Ultraviolet Spectra (UV), and Gel Permeation Chromatography (GPC). Micelles self assembled from FA-DMP copolymers were prepared through dialysis method. Results showed that mPEG could effectively initiate the ring opening polymerization of DTC without catalyst, and that the molecular weight of DMP copolymers could be adjusted by changing the molar feed ratio of DTC to mPEG. The folate-conjugated DMP copolymers could form nano-micelles, and the size was related to the hydrophilic-hydrophobic chain length of copolymer.