Stable nanoemulsions prepared via interfacial solidification of amphiphilic polyether-polyester block copolymers.

Oil-in-water (O/W) emulsions are generally stabilized by water-soluble surfactants, which anchor to the surface of oil droplets dispersed in an aqueous solution. Our recent work introduced a new approach to stabilize nanoemulsions through the formation of a semi-solid interphase at the O/W interface using a water-insoluble amphiphilic block copolymer, methoxy poly(ethylene glycol)-block-poly(ɛ-caprolactone). However, the approach is not applicable to relatively non-polar oils due to the quick precipitation of the hydrophobic PCL block within the oil phase. Here we report on successful stabilization of non-polar liquid paraffin nanoemulsions using an amphiphilic copolymers having a new hydrophobic block comprising ɛ-caprolactone and L-lactide. The new block copolymer was reorganized at the O/W interface of liquid paraffin, generating stable nano-sized emulsions via the formation of a robust semi-solid polymeric barrier. The prepared nanoemulsions show excellent dispersion stability even under a high level of mechanical stresses during freeze/thaw cycles.