Polymerization of cationic surfactant phases

Mixtures of polymerizable surfactants have been employed to select control over interfacial curvature phase structure, in aqueous micelles, lyotropic; mesophases, and water-in-oil microemulsions. These surfactants were 11-(me thacryloyloxy)undecyltrimethylammonium bromide (A), dodecyl(11-(methacryloy loxy)undecyl)dimethylammonium bromide (B), and cetyltrimethylammonium 4-vin ylbenzoate (C). The single chain A and double chain B have reactive hydroph obic 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 soluti ons. Polymerization was confirmed by disappearance of characteristic vinyl signals in the H-1 NMR spectra, and line broadening, as would be expected i n polymerized micelles. Furthermore, small-angle neutron scattering (SANS) indicates that micelle structures were broadly retained after polymerizatio n. SANS has shown that these polymerized structures persist below the criti cal micelle concentration of the nonpolymerized system. With lyotropic meso phases, polarizing light microscopy coupled with SAXS indicates retention o f the lamellar (L-alpha) phase after polymerization and, for hexagonal (H-1 ) phases, evidence for long-range order in the polymerized sample. Finally, films in water-in-oil microemulsions composed of A and B surfactant mixtur es were also studied. After polymerization, NMR indicated around 35% conver sion to the surface-active polymer. SANS showed that the droplet size may b e tuned by film composition and that the parent droplet structure was retai ned after polymerization.