Characterization of the Solutol® HS15/Water Phase Diagram and the Impact of the Δ9-Tetrahydrocannabinol Solubilization

Here, the phase behavior of the commercial nonionic surfactant Solutol® HS15 in water was investigated. The focus was on the evolution of the system nanostructure at low water content. Particularly, it was demonstrated that at low water content spherical micelles are present. Micelles coalesce at a surfactant volume fraction close to 0.5. As consequence, a heterogeneous pseudo-binary mixture occurs. No liquid crystalline phases were detected even at the highest HS15 concentrations in water. A morphological change of the micelles occurred on addition of the cannabinoid 9-tetrahydrocannabinol (THC). THC is entrapped within the surfactant tails modifying the micelle shape. At sufficiently low water content (18-35 wt%) such alteration of the interfacial packing results in a lamellar organization of the surfactant molecule