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Two series of Aerosol-OT-analoguesurfactants (sulfosuccinate-typedi-BCnSS and sulfoglutarate-type di-BCnSG) with hyperbranched alkyl double tails(so-called “hedgehog” groups, carbon number n= 6, 9, 12, and 18) have been synthesized and shown todemonstrate interfacial properties comparable to those seen for relatedfluorocarbon (FC) systems. Critical micelle concentration (CMC), surfacetension at the CMC (γCMC), and minimum area per molecule(Amin) were obtained from surface tensionmeasurements of aqueous surfactant solutions. The results were examinedfor relationships between the structure of the hedgehog group andpacking density at the interface. To evaluate Aand Bvalues in the Klevens equation for these hedgehog surfactants,log(CMC) was plotted as a function of the total carbon number in thesurfactant double tail. A linear relationship was observed, producing Bvalues of 0.20–0.25 for di-BCnSS and di-BCnSG, compared to avalue of 0.31 for standard double-straight-tail sulfosuccinate surfactants.The lower Bvalues of these hedgehog surfactantshighlight their lower hydrophobicity compared to double-straight-tailsurfactants. To clarify how hydrocarbon density in the surfactant-taillayer (ρlayer) affects γCMC, theρlayerof each double-tail surfactant was calculatedand the relationship between γCMCand ρlayerexamined. As expected for the design of low surface energysurfactant layers, ρlayerwas identified as an importantproperty for controlling γCMCwith higher ρlayer, leading to a lower γCMC. Interestingly,surfactants with BC9and BC12tails achievedmuch lower γCMC, even at low ρlayervalues of <0.55 g cm–3. The lowest surfaceenergy surfactant studied here was di-BC6SS, which hada γCMCof only 23.8 mN m–1. Sucha low γCMCis comparable to those obtained with shortFC-tail surfactants (e.g., 22.0 mN m–1for the sulfosuccinate-typeFC-surfactant with R = F(CF2)6CH2CH2−). [ABSTRACT FROM AUTHOR]