Programmable Liquid Crystal Defect Arrays via Electric Field Modulation for Mechanically Functional Liquid Crystal Networks

Abstract

The arrangement of mesogenic units determines mechanical response of the liquid crystal polymer network (LCN) film to heat. Here, we show an interesting approach to programming three-dimensional patterns of the LCN films with periodic topological defects generated by applying an electric field. The mechanical properties of three representative patterned LCN films were investigated in terms of the arrangement of mesogenic units through tensile testing. Remarkably, it was determined that LCN films showed enhanced toughness and ductility as defects increased in a given area, which is related to the elastic modulus mismatch that mitigates crack propagation. Our platform can also be used to modulate the frictional force of the patterned LCN films by varying the temperature, which can provide insight into the multiplex mechanical properties of LCN films.

Photothermal-Driven Liquid Crystal Elastomers: Materials, Alignment and Applications

“…where 𝐾 is the Frank elastic coefficient, 𝜀 is the permittivity of free space, Δ𝜀 = 𝜀 ∥ − 𝜀 is the anisotropy of the dielectric susceptibility, and 𝑑 is the cell thickness [54,55]. You et al [56] used striated indium-tin oxide (ITO) electrodes with different widths and distances on glass substrates to design cells that could align liquid crystal monomers by an electric field. Electrodes with pattern information made it possible to induce a periodic arrangement of the liquid crystal elastomer, which in turn changed the specific mechanical properties of the LCE such as surface friction coefficient, toughness, and ductility.…”

Regulating Surface Topography of Liquid‐Crystalline Polymers by External Stimuli

“…Reproduced with permission. [ 113 ] Copyright 2021, American Chemical Society. e) The deformation of a honeycomb structure with various mesogenic directors under a magnetic field.…”

“…Recently, You et al applied alternating current (AC) electric fields with different amplitudes to modulate the LC directors and in turn periodic micropatterns of LC defects were obtained. [113] As shown in Figure 12a, the red and blue stripes represent the top and bottom electrodes, respectively. The LC mixture composed of two mesogenic monomers and one photoinitiator was filled in the three kinds of LC cells.…”

“…When the LCN coating was exposed to UV light only, the height difference between the peak and valley was about 600 nm. If the AC electric field was applied [113] Copyright 2021, American Chemical Society. e) The deformation of a honeycomb structure with various mesogenic directors under a magnetic field.…”

“…d) The conformation and activation force density in one unit of LC cell 3. Reproduced with permission [113]. Copyright 2021, American Chemical Society.…”