Fast Fabrication of Sub-200-nm Nanogrooves Using Liquid Crystal Material

Abstract

Self-assembly of soft materials attracts keen interest for patterning applications owing to its ease and spontaneous behavior. We report the fabrication of nanogrooves using sublimation and recondensation of liquid crystal (LC) materials. First, well-aligned smectic LC structures are obtained on the micron-scale topographic patterns of the microchannel; then the sublimation and recondensation process directly produces nanogrooves having sub-200-nm scale. The entire process can be completed in less than 30 min. After it is replicated using an ultraviolet-curable polymer, our platform can be used as an alignment layer to control other guest LC materials.

Role of Stimuli on Liquid Crystalline Defects: From Defect Engineering to Switchable Functional Materials

“…Polymers having either LC molecular-philic or -phobic properties are put on a substrate by the spin-coating method. Frequently encountered polymeric materials are polyimide (PI) [33], polyethyleneimine (PEI) [34], and polyvinyl alcohol (PVA) [35]. Some reported methods for surface treatment involve self-assembled monolayers (SAMs) [36,37].…”

“…Since Choi et al [50] reported the exploitation of microchannels to generate periodic smectic defects, many experimental results using microchannels have been obtained [17,28,33,34,[51][52][53][54][55]. As LC materials should adopt a specifically defined orientation under limited volume and surface conditions of microchannels, the so-called confinement effect, they develop a peculiar structure in a periodic manner.…”

Surface Azimuthal Anchoring Energy Between the Grating Surface and Nematic Liquid Crystal Layer Studied by Using a Geometric Model

“…However, the rubbing process not only creates scrap, but also an electrostatic charge, which adversely affects the alignment of the liquid crystals. Accordingly, various alternative techniques for fabricating the crystal alignment layer have been proposed [1][2][3][4][5][6][7][8][9]. For example, Newsome et al [1] used a laser ablation technique to pattern grating structures on a polymer layer.…”

“…Gear et al [8] demonstrated that patterned nanogrooves using electron beam lithography can be used to control the magnitude of the azimuthal anchoring energy of liquid crystals. Kim et al [9] reported the fabrication of nanogrooves having sub-200-nm scale and the entire process can be completed in less than 30 minutes. In general, the results presented in [1][2][3][4][5][6][7][8][9] indicate that the molecular orientation of liquid crystals is significantly dependent on the shape of the grating pattern.…”

“…Kim et al [9] reported the fabrication of nanogrooves having sub-200-nm scale and the entire process can be completed in less than 30 minutes. In general, the results presented in [1][2][3][4][5][6][7][8][9] indicate that the molecular orientation of liquid crystals is significantly dependent on the shape of the grating pattern. The surface azimuthal anchoring energy is one of the most important factors in characterizing the surface orientation of liquid crystal molecules [10].…”