CONTROL OF THE STRUCTURE OF LANGMUIR-BLODGETT-FILMS OF A DISCOTIC LIQUID-CRYSTALLINE COMPOUND VIA THE SUBPHASE COMPOSITION AND THE ADJACENTMOLECULAR ENVIRONMENT

Changes of the molecular arrangement that can be induced by means of t he LB technique in the multilayers of a disc-shaped multialkynyl amphi phile are monitored by means of small angle X-ray diffraction. Studies of the monolayers at the air-water interface reveal ''edge-on'' orien tation of the discs. Specific effects of the counterions (Na+, Cd2+, P b2+ and Ba2+) and sub-solution pH on the monolayer collapse pressure, transfer efficiency and molecular order in the multilayers are found. A correlation between the monolayer properties and the ability for for mation of periodic discotic structures in the presence of divalent cou nterions is established. The discotic molecules retain their ''edge-on '' arrangement in the highly compressed transferred films with slight irregular interdigitation of the flexible wings and inclination to the substrate normal. The tilt and the interdigitation are reduced when t he discotic monolayers are deposited in alternating LB films with bari um arachidate spacer layers.