Two series of Aerosol-OT-analogue surfactants (sulfosuccinate-type di-BCnSS and sulfoglutarate-type di-BC(n)SG) with hyperbranched alkyl double tails (so-called "hedgehog" groups, carbon number n = 6, 9, 12, and 18) have been synthesized and shown to demonstrate interfacial properties comparable to those seen for related fluorocarbon (PC) systems. Critical micelle concentration (CMC), surface tension at the CMC (gamma(CMC)), and minimum area per molecule (A(min)) were obtained from surface tension measurements of aqueous surfactant solutions. The results were examined for relationships between the structure of the hedgehog group and packing density at the interface. To evaluate A and B values in. the Klevens equation for these hedgehog surfactants, log(CMC) was plotted as a function of the total carbon number in the surfactant double tail. A linear relationship was observed, producing B values of 0.20-0.25 for di-BCnSS and di-BC(n)SG, compared to a value of 0.31 for standard double-straight-tail sulfosuccinate surfactants. The lower B values of these hedgehog surfactants highlight their lower hydrophobicity compared to double-straight-tail surfactants. To clarify how hydrocarbon density in the surfactant-tail layer (rho(layer)) affects gamma(CMC), the rho(layer) of each double-tail surfactant was calculated and the relationship between gamma(CMC) and Player examined. As expected for the design of low surface energy surfactant rho(layer) was identified as an important property for controlling gamma(CMC) with higher rho(layer) leading to a lower gamma(CMC) Interestingly, surfactants with BC9 and BC12 tails achieved much lower gamma(CMC), even at low rho(layer) values of <0.55 g cm(-3). The lowest surface energy surfactant studied here was di-BC6SS, which had a gamma(CMC) of only 23.8 mN m. Such a low gamma(CMC) is comparable to those obtained with short FC-tail surfactants (e.g., 22.0 mN m(-1) for the sulfosuccinate-type FC-surfactant with R = F(CF2)(6)CH2CH2-).