| 초록 |
A series poly (lactic acid) (PLA) and poly (ethylene glycol) (PEG) multiblock copolymers with relatively high molecular weight were synthesized through the coupling reaction between the bischloroformates of carboxylated PLA and PEG. The synthetic rout included three steppes. First, the dicarboxylated PLA was obtained through the polycondensation reaction of lactic acid using succinic acid as molecular weight controller. And the reactivity of the dicarboxylated PLA was increased reacting with thionyl chloride. Finally, the bifunctionalized PLA and PEG were coupled in the presence of pyridine. The copolymer composition and multiblock structure were confirmed by NMR and GPC measurements. The melting temperature Tm of the PEG domain was influenced by the relative length of the PCL and PEG blocks. This was caused by the strong covalent interconnection between the two domains. The critical micelle concentration was determined to be 16–81mg/l by surface tension technique, depending on the length of PCL blocks and PEG blocks. |
