Self-assembly in surfactant-based liquid mixtures: Bis(2-ethylhexyl)phosphoricacid/bis(2-ethylhexyl)amine systems

Surfactant-based liquid mixtures constitute an interesting class of nanostructured materials with promisingpotential in specialized applications. Here, structural and conductometric properties of liquid mixturescomposed of bis(2-ethylhexyl)amine (BEEA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) havebeen thoroughly investigated with the aim to correlate structural features with system charge transportcapability. The evolution of self-assembled local nanostructures with system composition has been investigatedby FT-IR and XRD while the conductometric properties were probed by conventional AC compleximpedance. Both pure components exhibit nano-segregation due to their amphiphilic nature but withonly very low proton conductivities. However their mixtures, characterized by local organization of polarand apolar domains driven by acid–base interactions between HDEHP PO4H and BEEA NH groups, showenhanced structural order and proton conductivity.