Pii: S0032-3861(98)00378-4

A novel method for the preparation of solvent-free poly(«-caprolactone) (PCL) microspheres from PCL/poly(ethylene glycol) (PEG) blends was developed and demonstrated. The particle size of the PCL spheres are in the range of 1 to 20 mm (mostly in the range 5–10 mm). The influences of the molecular weight of PCL, the molecular weight of PEG, the type of emulsifier, the concentration of plasticizer, the homogenization time and temperature on the characteristics of the PCL microparticles were also investigated. No changes in PCL molecular weight distribution and peak shape were observed, which indicates that the PCL matrix is stable during the fabrication process. However, the microspheres made from low-molecular-weight PCL coalesced into a continuous mass on drying and lost their properties as individual spheres. The surface of the PCL microspheres prepared from PEG 300 as the external phase at 708C is much smoother than that of the other formulations. The major advantage of this polymer-blend melt technique compared with traditional methods for microsphere preparation is the elimination of methylene chloride or other organic solvents for polymer solubilization. Therefore, the toxicity associated with organic solvent residues resulting from conventional solvent preparation of microspheres is not present with this polymer-blend melt technique. q 1999 Elsevier Science Ltd. All rights reserved.