The authors express their gratitude to the Spanish Ministry of Science and Innovation for their support through PID2021-122187NB-C31 (Knowledge Generation Projects, 2021) and TED2021-130476B-I00 (Strategic Projects Focused on Ecological and Digital Transition, 2021) research projects. Gratitude is also extended to the European Regional Development Fund (FEDER) and the AEI (Agencia Estatal de Investigación) for their support of Spanish research programs. The “Grupo de Nanotecnología Farmacéutica” at the Univrsity of Barcelona (UB), which is an Associated Unit to the CSIC, is acknowledged as well. The optical microscopy observations were performed at the Nanostructured Liquid Characterization Unit within the Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), which is part of the NANBIOSIS ICTS of the CIBER-BBN. The authors also thank Clara Jaén, currently in IDAEA-CSIC, for measuring cloud temperatures, and Sonia Pérez (”Joan Carilla” Thermal Analysis and Calorimetry Service, IQAC-CSIC) for DSC determinations.

Water-in-water (W/W) emulsions can be obtained when two water-soluble components are mutually immiscible. The scientific literature on W/W emulsions focuses on polymer-polymer mixtures, with only a few reports on polymer-salt systems, and no documented cases involving polymer-surfactant mixtures. Our hypothesis was that by lowering the cloud temperature of a surfactant through the addition of a polymer, phase segregation into two immiscible aqueous solutions could enable the formation of W/W emulsions.

Peer reviewed