Highlights - Satoshi Aya Soft Matter Lab. @Guangzhou

Highlights

An extended mean-field theory for achiral and chiral ferroelectric nematic fluids is validated and tested. Simulations based on the theory show diverse topological structures for ferroelectric nematic droplets (PCCP, 2024).

Chiral and polar nematic fluids, dubbed the helielectric nematics, exhibit a novel type of polar topology driven by flexoelectricity. The topology arises as a general feature for polar and chiral systems developing from an isotropic background (Nat. Phys. 2024).

Ferroelectric nematics serve as a spontaneous polar field for aligning polar entities, which results in drastic increase of second-harmonic output (JMCC, 2023).

A new type of polar liquid crystal phase, dubbed ferroelectric smectic-A phase was discovered. It adds the 1D positional order to the ferroelectric nematic phase (JPCL, 2022).

Traditionally, it is difficult to control the alignment of polarizations in materials, limiting explorations of polarization structures and the resultant electrooptic effects. This work shows the spontaneous polar helix can realize a mechanism for phase-matched second-harmonic generation (PNAS, 2022).

By a design of sequencial alignment of dipoles in oligomers, we realize the ferroelectric nematic state by the enhanced dipole-dipole interactions along the axis of molecules (JACS, 2021).

By building an instrument for second-harmonic harmonic and its interferometry, for the first time, we visualize and discover the polar and chiral nematic phase, dubbed the helielectric nematic phase, in the real space (PNAS, 2021).

We reveal a pathway for generating oscilating solitonic orientational field in the nematic phase. By varying the amplitude and frequency of the external electric field, the motion of the nematic solitons can be controlled (Nat. Commun., 2020).

Ferroelectric nematic droplets exhibits distinct textures to those in apolar nematics. Now, we found that there are two types of primary polar textures, i.e., polar vortex-like and line disclination mediated structures, dominately driven by flexoelectricity and electrostatic (or depolarization field) effect (Soft Matter, 2024).

In the emerging polar and chiral nematic phase, dubbed helielectric nematic phase, the competition between polar interactions and compressive elasticity, results in a spontaneous buckling instability (PNAS Nexus, 2023).

Ferroelectric nematics exhibit unique meron-like polarization topology under a cylindrical confinement (Nat. Commun., 2022).

While the shape anisotropiy serves as an important traditional driving force for realizing apolar nematic phase, polarity is another type of anisotropic driving force for realizing polar nematic state. This leads to a direct isotorpic-ferroelectric nematic phase transition, particularly when the shape anisotropy is NOT enough for forming the nematic phase (Giant, 2022).

For the well-known ferroelectric nematic molecule, DIO, we show a strong stereoisomer effect for stablizing the ferroelectric nematic phase by mixing the trans- and cis-conformers. The electrooptic properties like spontaneous polarization also change dramatically. Under proper mixing conditions, the ferroelectric nematic phase is significantly stablized (JMCC, 2022).

By systematically designing and testing main-chain and side-chain types of polar polymeric liquid crystal materials, we show polar nematic state with high SHG intensity can be achieved (Macromolecules, 2021).

We demonstrate extreme modulation of nematic viscoelasticity triggered by a reversion of the ester bond direction in two series of sulfur-containing cyanobiphenyl-based LC dimers. An extraordinarily enhanced viscoelastic properties (up to about 1000 times) was found (JMCC, 2021).

By combining machine learning and massive synthesis, we vationalize a guideline for generating ferroelectric nematic state. Based on several tens of new molecules, we systematically studied the topology and electroopic properties, e.g., spontaneous polarization and second-harmonic generation, of the ferroelectric nematic materials (Sci. Adv., 2021).