Effect of ionic liquids on the cloud points of PEG-PPG-PEG triblock copolymer and the formation of aqueous two-phase micellar systems as platforms for the encapsulation of drugs

Polymeric micelles obtained by aqueous two-phase micellar systems (ATPMS) hold a large potential for cloud point (CP) extraction/encapsulation of drugs but are yet poorly characterized and studied (Vicente et al., 2017), hence limiting their employment in formulations. This work reports the effect of different cholinium-based ionic liquids (ILs) upon the clouding behavior of PEG-PPG-PEG triblock copolymer. The influence of the ILs on the binodal curves was dependent on the concentration and type of ILs added to the ATPMS. In this sense, the effects on the displacement of the CP increased with the increase of ILs concentration (M), i.e. from 3.0 M to 0.5 M. It was also shown that the reduction of CP follows the trend: [Ch][Hex] > [Ch][But] > [Ch][Prop] > [Ch][Ac] > [Ch]Cl. In summary, the biphasic region increased and the CP decreased, i.e. close to room temperature: 25 to 30ºC, with ILs addition (Figure 1).