Universal Surfactant for Water, Oils, and CO2

A trichain anionic surfactant sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulfonate (TC14) is shown to aggregate in three different types of solvent: water, heptane, and liquid CO2. Small-angle neutron scattering (SANS) has been used to characterize the surfactant aggregates in water, heptane, and dense CO2. Surface tension measurements, and analyses, show that the addition of a third branched chain to the surfactant structural template is critical for sufficiently lowering the surface energy, tipping the balance between a CO2-incompatible surfactant (AOT) and CO2-philic compounds that will aggregate to form micelles in dense CO2 (TC14). These results highlight TC14 as one of the most adaptable and useful surfactants discovered to date, being compatible with a wide range of solvent types from high dielectric polar solvent water to alkanes with low dielectrics and even being active in the uncooperative and challenging solvent environment of liquid CO2.