Healing of Defects at the Interface of Nematic Liquid Crystals and Structured Langmuir-Blodgett Monolayers

Stirring competes with chemical induction in chiral selection of Langmuir monolayer domains

“…We would like to stress the remarkable finding that a three-dimensional physical force (vortical stirring), operating in centimeter-length scales can couple to the chemical effect of a supramolecular level modifier. Our contribution should also be envisaged, upon transference of the monolayer onto a solid support [14], as a new strategy for stereocontrol of chemical reactions and responses at chiral surfaces.…”

Topological defects in cholesteric liquid crystals induced by monolayer domains with orientational chirality

“…The plates were subsequently 20 cooled, rinsed with abundant Milli-Q water and dried thoroughly with a stream of nitrogen. One of the plates was patterned by LB transfer of monolayers of the surfactant 4-[4-[4-octylphenyl/azo]phenoxy]butanoic acid (8Az3COOH), previously self-assembled at the air/water interface in the form of isolated islands at low lateral pressure (< 1 mN/m), as described previously 20 . This process was carried out using either a Nima 600 Series LB instrument or a custom-made system at room temperature and using a dipper speed of 1 mm/min.…”

“…In contrast to these artificial patterning methods, complex 3D configurations can be imprinted in LCs through interaction with self-assembled surfactant monolayers formed by means of the Langmuir-Blodgett (LB) technique 18,19 . In a recent work 20 , we have shown that the patterns of molecular alignment present in Langmuir monolayers of an azobenzene surfactant can be transferred into a nematic LC by confining the mesogen between a glass plate coated with the LB film and a complementary plate treated for planar alignment, the latter of which sets the homogeneous far field LC orientation ( Fig. 1).…”

“…21 When in contact with the LB film, the LC director n(r) follows the local in-plane orientation of the surfactant monolayer ( Fig. 1) 18,20,22 . The anchoring angle with respect to the surface normal is similar throughout the LB film (35° -45°), but outside the domains surfactant molecules are disordered, and the LC director adopts an in-plane alignment set by the complementary plate.…”

Antipersistent behavior of defects in a lyotropic liquid crystal during annihilation

“…One of the main aspects of the ordering process is the dynamical behavior of defects present in the material. Topological defects appear in several systems that present some kind of ordering [12][13][14][15][16][17]. Alloys [18], semiconductors [19], polymers [20] and liquid crystals [21,22] are just a few examples.…”