Synthesis And Micellization Of Biodegradable MPEG-b-PCL-b-PEEP Block Copolymer

Methoxy polyethylene glycol/polycaprolactone(mPEG-b-PCL) was synthesized by ring opening polymerization(ROP) ofε-caprolactone(CL) and then it was used as macroinitiator to initiate ring opening polymerization of EEP to produce methoxy polyethylene glycol/polycaprolactone/polyphosphoester(mPEG-b-PCL-b-PEEP) triblock copolymer. The structure of the copolymer was determined by infrared (IR), 1H nuclear magnetism (1H-NMR) and the gelatin seepage chromatography (GPC). The micelles of the copolymer were prepared. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer micelle solution. The diameter and distribution of micelles were characterized by dynamic light scattering(DLS) and its shape was observed by transmission electron microscopy(TEM).The results showed that MPEG-b-PCL could be prepared by ROP of CL and it could initiate the ROP of EEP to give MPEG-b-PCL-b-PEEP. These copolymers could self-assemble into nano-micelles in water. The CMC of copolymer solution and the size of micelle reduced with the increasing of the proportion of hydrophobic parts. Such block copolymers could be expected to find applications in drug delivery systems and other biomedical fields.