Synthesis And Micellization Of Copolymer By Microwave

Methoxy polyethylene glycol/poly(ε-caprolactone)/polylactide amphiphilic triblock copolymer(MPEG-b-PCL-b-PDLLA) was synthesized by ring opening polymerization of D,L-lactide (DLLA) initiated by hydroxyl-terminated methoxy polyethylene glycol/poly(ε-caprolactone) block copolymer(MPEG-b-PCL-OH), which was prepared by ROP ofε-caprolactone(CL) initiated by methoxy polyethylene glycol(MPEG) under microwave assistant. The structures of the copolymers were determined by infrared spectroscopy (IR), nuclear magnetic resonance (1H NMR) and gel permeation chromatography(GPC). The micelles of MPEG-b-PCL-b-PDLLA were prepared. The steady-state fluorescence spectrometry was used to determine the critical micelle concentrations (CMC) of copolymer micelle solution. The diameter and distribution of the micelles were characterized by dynamic light scattering(DLS).The results showed that, MPEG could initiate ROP of CL to form MPEG-b-PCL-OH, which could initiate ROP of DLLA to form MPEG-b-PCL-b-PDLLA. MPEG-b-PCL-b-PDLLA could self-assemble into nano-micelles with hydrophilic shell and nano-micelle hydrophobic core in water. Critical micelle concentration increased with the ratio of the rigid segment of PDLLA chains, micelle particle increased with the ratio of the rigid segment of PDLLA chains. By changing the ratio of flexible chains and rigid chain , size of copolymer micelles was adjusted.