Effects of polymerization on chromophore stacking in bilayer membranes

Two novel polymerizable double-chained ammonium amphiphiles carrying mesogenic cyanobiphenylyloxy units have been synthesized containing methacrylate in the headgroup or diacetylene groups in the hydrophobic tails. These compounds form bilayer vesicles upon dispersion in water. Polymerization increases the vesicle stability toward solubilization by a nonionic surfactant. The stacking of the cyanobiphenylyloxy units in the bilayer is directly monitored by the extent of the blue shift of the absorption maximum. Upon polymerization a decrease in blue shift is observed, reflecting a decrease in the ordering of the amphiphile molecules. This effect is stronger when polymerization occurs in the hydrophobic tails than in the headgroup region.