Studies on one-dimensional confinement system for self-ordered helical nanofilament liquid crystal phase

Abstract

Bent-core molecules, the first group of achiral mesogens have attracted significant attention due to their polar and chiral properties. To control the unusual structural properties of B-phases in large domain, aligning control of B-phase in the topologically controlled confined geometries can be a good candidate. Anodic aluminum oxide (AAO) membrane composed of hexagonal, closely packed nanochannel arrays has good structural potentials as host and templating materials for metal/metal oxide nanowires, energy storage, catalysts and sensor system. Here, we describe the spontaneous transformation of morphology and configuration of bent-core liquid crystal confined in chemically modified AAO. Helical nanofilaments (HNFs) and nanodisk mesophase transformation could be naturally formed merely depending on surface chemical properties with same mesogen. Furthermore, We have investigated various morphological changes of the HNF phases in multi-scale nanochannels made of the AAO film. Single or multi-helical structures could be manipulated depending on the AAO pore size and the higher-temperature phase of each molecule. The nanostructures of HNFs affected by the chemical affinity between the molecule and surface were drastically controlled in surface-modified nanochannels. To diverse the confinement geometry of nanochannel hosts, we studied the growth mechanism of pre-patterned nanochannel arrays with 100 - 240 nm interpore distances using focused ion beam li-thography. Electron microscope cross section images of the induced nanochannel revealed the cor-relation between the interpore distances and pore length measured to the branching point based on a quantitative analysis. Our approaches on bent-core liquid crystal confinement effect in chemically/physically modified AAO nanochannel will be helpful for improved understanding of the fundamental studies on mesophase confined in one-dimensional nanochannels.