The behavior of poly(ethylene glycol)-b-poly(butylene terephthalate) copol ymer has been investigated. The influences of the immersing time(in phosphate buffer solution of pH=7 4, at (37±1) ℃) on the sw elling ratio, the mass loss and the surface morphology of the copolymer film were examined. The copolymer is found to be degradable. The m icrospheres of PEG-b-PBT were prepared by a solvent extraction method using PVA as a stabilizer and characteristic of a sm ooth and spherical surface, sized about 1 133 μm. IR and XRD results reveal that Levonorgestrel crystalls are physically entrapped in the microspheres of the copolymer.
