INVESTIGATION OF BULK PROPERTIES AND MONOLAYER BEHAVIOR OF AMPHIPHILIC MESOGENS - STRUCTURAL VARIATIONS OF THE HEAD GROUP

Non-ionic amphiphilic compounds-butane-1,2,3-triol derivatives. 2-hydr oxycarboxylic acids and carboxylic acids-incorporating rigid aromatic structural units like 1,4-disubstituted benzene. 4,4'-disubstituted bi phenyl or the 2-phenyl-1,3,4-thiadiazole have been prepared. In most c ases these compounds exhibit smectic liquid crystalline phases which c an be stabilized by the addition of water. Their mesomorphic propertie s are compared with those of the structurally related 1,2-diol derivat ives. Surprisingly, also some omega-(4-alkylphenoxy)alkanoic acids whi ch have no thermotropic mesophases were found to aggregate to lyotropi c mesophases in the presence of water. Most of the new compounds form stable monolayers at the air-water interface. The force-area isotherms of the thiadiazole derivatives have been recorded and it was found th at they strongly depend on the chemical structure of the head group.