A novel fabrication of poly(epsilon-caprolactone) microspheres from blendsof poly(epsilon-caprolactone) and poly(ethyleneglycol)s

A novel method for the preparation of solvent-free poly(epsilon-caprolacton e) (PCL) microspheres from PCL/poly(ethylene glycol) (PEG) blends was devel oped and demonstrated. The particle size of the PCL spheres are in the rang e of 1 to 20 mu m (mostly in the range 5-10 mu m). The influences of the mo lecular 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 proce ss. However, the microspheres made from low-molecular-weight PCL coalesced into a continuous mass on drying and lost their properties as individual sp heres. The surface of the PCL microspheres prepared from PEG 300 as the ext ernal phase at 70 degrees C is much smoother than that of the other formula tions. The major advantage of this polymer-blend melt technique compared wi th traditional methods for microsphere preparation is the elimination of me thylene chloride or other organic solvents for polymer solubilization. Ther efore, the toxicity associated with organic solvent residues resulting from conventional solvent preparation of microspheres is not present with this polymer-blend melt technique. (C) 1999 Elsevier Science Ltd. All rights res erved.