Study of the mechanisms of formation of nanoparticles and nanocapsules of polyisobutyl-2-cyanoacrylate

Biodegradable colloids suitable for use as drug delivery systems can be formed by in situ polymerization of isobutylcyanoacrylate monomers. In this work we have studied the mechanisms of formation of colloidal systems of PIBCA obtained in the presence of oil and ethanol. For this different analytical techniques have been used (TEM, PCS, GPC). The results have shown that the diffusing ethanol was the most important factor which leads to the structure and colloidal characteristics of the particles by convective effects, the oil playing the role of a monomer support. The existence of an ideal oil/ethanol ratio (2:100) seems to result from the combination of both mechanisms. In the absence of oil and ethanol, IBCA polymerization occurs within micelles appearing in the aqueous phase. However, in the case of nanocapsule formation, owing to the solubility of the monomer in the organic phase and the diffusibility of ethanol, polymerization can develop at the interface. In this latter case, the formation of a double population of nanocapsules and nanoparticles probably arises from the breakdown of the same interfacial polymer.