Langmuir-Blodgett film organization resulting from asymmetrical or partial types of monolayer transfer: Comparison for amphiphiles of different geometrical shapes

The problem of whether the Langmuir-Blodgett (LB) technique is capable of producing ordered films of molecular arrangement different from a bulk phase one is addressed for amphiphiles of rod-like and disk-like geometrical shapes. Low-angle X-ray diffraction and morphological characterization are performed for LB films deposited by means of asymmetrical and partial types of monolayer transfer. The influence of thermodynamic parameters, steric molecular peculiarities, and intermolecular interactions on the efficiency and mechanism of the monolayer transfer is considered. Molecular overturning to a multibilayer (''bulk'') arrangement is established for the case of Z-type (one-direction up-stroke) deposition of the rod-like amphiphile, and a crystalline body-centered orthorhombic (''bulk'') structure for the case of partial (''mixed'' XY type) LB transfer of the diskotic films. Symmetrical Y-type deposition is found to result in almost defect-free multilayers over large scales of film surface examination. For both kinds of amphiphiles studied, the asymmetrical and partial types of LB transfer are less effective, as compared to the Y-type, in inducing periodic thin film organizations, distinct from the bulk phase structures of the amphiphiles.