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6880685 
Journal Article 
Biscationic bicephalic (double-headed) amphiphiles with an aromatic spacer and a single hydrophobic tail 
Roszak, KZ; Torcivia, SL; Hamill, KM; Hill, AR; Radloff, KR; Crizer, DM; Middleton, AM; Caran, KL; , 
2009 
Yes 
Journal of Colloid and Interface Science
ISSN: 0021-9797
EISSN: 1095-7103 
ACADEMIC PRESS INC ELSEVIER SCIENCE 
SAN DIEGO 
560-564 
19118840 
WOS:000263335700047 
We report the synthesis and aggregation studies of a homologous family of biscationic "bicephalic" amphiphiles. Each of has a linear alkoxy chain and two trimethylammonium bromide headgroups connected to a benzene ring. Krafft temperatures (T-K) in water were determined by differential scanning calorimetry (DSC) and conductivity. Critical micelle concentration (cmc) and ionization degree (alpha) values were determined by monitoring the conductivity of aqueous solutions as a function of concentration, and confirmed by monitoring the H-1 NMR chemical shift of the terminal methyl group as a function of concentration. Values for log(cmc) decrease linearly with increasing chain length, with a smaller dependence on chain length than for single-headed amphiphiles, consistent with literature reports on other bicephalic amphiphiles. Comparison to two related amphiphiles, each with a single headgroup reveals that the addition of a second head group results in an increase in cmc and a decrease of TK. These effects are attributed to greater water solubility due to the incorporation of a second, hydrophilic headgroup. The effect on alpha is also discussed. (C) 2008 Elsevier Inc. All rights reserved.