ORIENTATION AND SPECTRAL CHARACTERISTICS OF THE AZOBENZENE CHROMOPHORE IN THE AMMONIUM BILAYER ASSEMBLY.

Azobenzene-containing, single-chain ammonium amphiphiles in which the alkyl chain length in the tail and spacer portions was systematically varied were prepared, and their aggregation behavior in water was studied by electron microscopy, differential scanning calorimetry and absorption spectroscopy. These amphiphiles exist as molecular dispersions, hydrated microcrystals, micelles, or bilayers. The formation of stable bilayers was deduced on the basis of three criteria which include the spectral agreement between aqueous dispersions and the corresponding cast films. Stable bilayers were obtainable when the sum of tail and spacer is not smaller than C//1//4 to C//1//6, and the tail is at least C//8.