Fluorosurfactants at Structural Extremes:  Adsorption and Aggregation

Fluorosurfactants with several structural modifications have been synthesized, and the air/water interface and bulk aggregation properties investigated. The compounds were fluorinated ethylene oxide (EO) nonionics where the number and position of the hydrophilic group(s) has been radically altered to generate linear, bolaform, and Y-shaped analogues. A noticeable structure−interfacial packing relationship was observed via both tensiometric measurements and neutron reflection studies:  the limiting molecular areas, acmc, and surface excesses, Γcmc, are strongly dependent on the number and position of the EO headgroups. Differing bulk aqueous properties were also observed. Small-angle neutron scattering shows an evolution of micelle structure from cylindrical to disklike aggregates on changing from Y-shaped to bolaform molecular structure.