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Résumé :
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Micelles of hydrophilic−hydrophobic block polymers, such as poly(ethylene glycol)−block-poly(ϵ-caprolactone) (PEG−b-PCL), used as drug-delivery carriers, are generally fabricated via solvent displacement or dialysis, which is time-consuming, requires freeze drying, and can leave toxic traces of the residual organic solvents. An alternative is presented in this paper: form micellar PEG−b-PCL nanoparticles in a supercritical fluid solvent and then disperse them in water toward a water-dispensable formulation. This method is illustrated with pressure−temperature phase diagrams for PEG−b-PCL in supercritical trifluoromethane, which is selective enough for the PCL and PEG blocks to induce micellization. When subjected to decompression to remove trifluoromethane, dry and organic solvent-free nanoparticles are readily obtained. Their micellar structure is immediately reestablished in water, as confirmed by laser light scattering. Neither has been demonstrated previously.
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