Polymerization of cationic surfactant phases

Mixtures of polymerizable surfactants have been employed to select control over interfacial curvature and phase structure, in aqueous micelles, lyotropic mesophases, and water-in-oil microemulsions. These surfactants were 11-(methacryloyloxy)undecyltrimethylammonium bromide (A), dodecyl(11-(methacryloyloxy)undecyl)dimethylammonium bromide (B), and cetyltrimethylammonium 4-vinylbenzoate (C). The single chain A and double chain B have reactive hydrophobic chain tips, whereas the single chain C possesses a polymerizable vinyl benzoate hydrophilic counterion. Aqueous micelles, composed of mixtures of these surfactants, can be polymerized to yield single-phase, stable solutions. Polymerization was confirmed by disappearance of characteristic vinyl signals in the ¹H NMR spectra, and line broadening, as would be expected in polymerized micelles. Furthermore, small-angle neutron scattering (SANS) indicates that micelle structures were broadly retained after polymerization. SANS has shown that these polymerized structures persist below the critical micelle concentration of the nonpolymerized system. With lyotropic mesophases, polarizing light microscopy coupled with SAXS indicates retention of the lamellar (L_α) phase after polymerization and, for hexagonal (H₁) phases, evidence for long-range order in the polymerized sample. Finally, films in water-in-oil microemulsions composed of A and B surfactant mixtures were also studied. After polymerization, NMR indicated around 35% conversion to the surface-active polymer. SANS showed that the droplet size may be tuned by film composition and that the parent droplet structure was retained after polymerization. Mixtures of polymerizable surfactants have been employed to select control over interfacial curvature and phase structure, in aqueous micelles, lyotropic mesophases, and water-in-oil microemulsions. These surfactants were 11-(methacryloyloxy)undecyltrimethylammonium bromide (A), dodecyl(11-(methacryloyloxy)undecyl)dimethylammonium bromide (B), and cetyltrimethylammonium 4-vinylbenzoate (C). The single chain A and double chain B have reactive hydrophobic chain tips, whereas the single chain C possesses a polymerizable vinyl benzoate hydrophilic counterion. Aqueous micelles, composed of mixtures of these surfactants, can be polymerized to yield single-phase, stable solutions. Polymerization was confirmed by disappearance of characteristic vinyl signals in the ¹H NMR spectra, and line broadening, as would be expected in polymerized micelles. Furthermore, small-angle neutron scattering (SANS) indicates that micelle structures were broadly retained after polymerization. SANS has shown that these polymerized structures persist below the critical micelle concentration of the nonpolymerized system. With lyotropic mesophases, polarizing light microscopy coupled with SAXS indicates retention of the lamellar (L_α) phase after polymerization and, for hexagonal (H₁) phases, evidence for long-range order in the polymerized sample. Finally, films in water-in-oil microemulsions composed of A and B surfactant mixtures were also studied. After polymerization, NMR indicated around 35% conversion to the surface-active polymer. SANS showed that the droplet size may be tuned by film composition and that the parent droplet structure was retained after polymerization.