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Updated: Jun 26, 2026

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Biscationic bicephalic (double-headed) amphiphiles with an aromatic spacer and a single hydrophobic tail
Karolina Z Roszak1, Stephanie L Torcivia, Kristina M Hamill
1James Madison University, Department of Chemistry and Biochemistry, MSC 4501, Harrisonburg, VA 22807, USA.
Abstract:
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 (1)H 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 T(K). These effects are attributed to greater water solubility due to the incorporation of a second, hydrophilic headgroup. The effect on alpha is also discussed.
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