MONOSIZE POLY(ETHYLCYANOACRYLATE) MICROSPHERES - PREPARATION AND DEGRADATION PROPERTIES

Monosize, biodegradable poly(ethylcyanoacrylate) (PECA) microspheres i n the size range of 0.5-2.5 mu m were prepared by a relatively new pol ymerization technique, the so-called dispersion polymerization. The po lymerizations were performed by using a stabilizer system containing a poly(ethyleneoxide)/poly(propyleneoxide) (PEO/PPO) copolymer and dext ran in the aqueous HCl solution as a dispersion medium. Phosphoric aci d was used as a catalyst, stabilizer, monomer concentrations, and the pH of dispersion medium on the monomer conversion, average size, and s ize distribution of the PECA microspheres were studied. The resultant microsphere size was mainly controlled by PEO/PPO copolymer and HCl co ncentrations. To explain the degradation mechanism, the degradation of monosize PECA microspheres was studied in in vitro conditions. The pa rtially degraded beads were observed by electron microscopy. The resul ts indicated that the degradation of monosize PECA microspheres occurr ed mainly by surface erosion. (C) 1995 John Wiley & Sons, Inc.