Synthesis and characterization of polyethylenglycohol based block copolymer

Poly ((ethylene glycol) methyl ether-b-lactide-b-ɛ-caprolactone) (mPEG-b-PLA-b-PCL) and poly (ɛ-caprolactone-b-lactide-b-(ethylene glycol)-b-lactide-b-ɛ-caprolactone) (PCL-b-PLA-b-PEG-b-PLA-b-PCL) were successfully synthesized via the combination of ring opening polymerization (ROP) and click chemistry. Poly (ethylene glycol) methyl ether-b-lactide) (mPEG-b-PLA) two-block and poly (lactide-b-(ethylene glycol)-b-lactide) (PLA-b-PEG-b-PLA) three-block copolymers were synthesized using ring-opening polymerization. mPEG-b-PLA-Br and Br-PLA-b-PEG-b PLA-Br block copolymers were prepared by the condensation of 2-bromopropionyl bromide with mPEG-b-PLA and PLA-b-PEG-b-PLA block copolymers. Azide-terminated mPEG-b-PLA-N3 and diazide-terminated N3-PLA-b-PEG-b-PLA-N3 block copolymers were obtained by nucleophilic substitution reactions in the presence of NaN3 with PEG-b-PLA-Br, Br-PLA-b-PEG-b-PLA-Br block copolymers. Well-defined precursor alkyne-functionalized PCL (alkyne-PCL) was prepared by ROP of ε-CL in the presence of different propargyl groups as the initiator and stannous-2-ethylhexanoate (Sn(Oct)2) as the catalyst. Click reaction, mPEG-b-PLA-b-PCL and PCL-b-PLA-b-PEG-b-PLA-b-PCL block copolymers were obtained with PCL-alkyne polymers PEG-b-PLA-N3 and N3-PLA-b-PEG-b-PLA-N3 block copolymers in the presence of Cu(I) catalyst. The characterization of the obtained block copolymers were carried out by using nuclear magnetic resistance (1H NMR), gel permeability chromatography (GPC), fourier transform ınfrared spectroscopy (FTIR).