Monosize poly(ethylcyanoacrylate) microspheres: preparation and degradation properties.

Monosize, biodegradable poly(ethylcyanoacrylate) (PECA) microspheres in the size range of 0.5-2.5 microns were prepared by a relatively new polymerization technique, the so-called dispersion polymerization. The polymerizations were performed by using a stabilizer system containing a poly(ethyleneoxide)/poly(propyleneoxide) (PEO/PPO) copolymer and dextran in the aqueous HCl solution as a dispersion medium. Phosphoric acid was used as a catalyst, stabilizer, monomer concentrations, and the pH of dispersion medium on the monomer conversion, average size, and size distribution of the PECA microspheres were studied. The resultant microsphere size was mainly controlled by PEO/PPO copolymer and HCl concentrations. To explain the degradation mechanism, the degradation of monosize PECA microspheres was studied in in vitro conditions. The partially degraded beads were observed by electron microscopy. The results indicated that the degradation of monosize PECA microspheres occurred mainly by surface erosion.