Molecular ordering & orientation of perfluorinated supramolecular liquid crystals in external fields

Abstract

We demonstrate the origin of planar alignment of self-assembled dendrimers on water surface by Langmuir-Blodgett method. π-A isotherm and BAM measurements show that the molecule forms a stable monolayer. TEM and AFM images of the condensed monolayer reveal that the molecule forms edge-on-oriented from with hexagonal packing. Upon further compression, the condensed monolayer is transformed into a multilayer, and the interfacial structure becomes planar morphology. The recognition of molecular ordering mechanism of perfluorinated fan-shaped molecule on the water subphase is important for understanding of thin film and surface induced nanostructure. Secondly, we report on the construction of supramolecular dendrimers consisting of highly oriented, cylindrical domains with long-range order using magnetic field. A very high degree of alignment is achieved in the magnetically oriented samples at low magnetic field strengths, which is a very important feature for many applications using supramolecular self-assemblies in the future electronics industry. Thirdly, we have shown the perfect ordering of toroidal domains with a very long range positional order and the direct observations of toroidal topology of Sm liquid crystal droplet on hydrophilic planar surface. Our experimental results show that the domain morphology, periodicity and ordering of the LCs are strongly influenced by the channel geometry. It would be possible to use this ordered toroidal domains not only for understanding topological transformations from isotropic to Sm focal phases, but also for the potential applications such as micro-pattering, bio-sensor, and particle trapper with sizes. Fourthly, we have suggested the mechanism of odd Rugby ball morphology and directly investigated this morphology by convolution technique with POM, SEM, and GISAXS. It should be possible to use the defect-free ordered optical patterns for optical grating and optical modulator using this system. Lastly, we pr...