David M. Walba
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View article: Thermotropic reentrant isotropic symmetry and induced smectic antiferroelectricity in the ferroelectric nematic material RM734
Thermotropic reentrant isotropic symmetry and induced smectic antiferroelectricity in the ferroelectric nematic material RM734 Open
We report a transition from the ferroelectric nematic liquid crystal (N F ) phase to a lower-temperature, apolar fluid phase having reentrant isotropic symmetry (I R ), in the liquid crystal compound RM734 doped with small concentrations o…
View article: Thermotropic reentrant isotropy and induced smectic antiferroelectricity in the ferroelectric nematic realm: comparing RM734 and DIO
Thermotropic reentrant isotropy and induced smectic antiferroelectricity in the ferroelectric nematic realm: comparing RM734 and DIO Open
We report the appearance of a liquid crystal phase having isotropic symmetry obtained by cooling a ferroelectric nematic with saturated polar order, a surprising new phenomen of the ferroelectric nematic realm.
View article: Double-Helical Tiled Chain Structure of the Twist-Bend Liquid Crystal Phase in CB7CB
Double-Helical Tiled Chain Structure of the Twist-Bend Liquid Crystal Phase in CB7CB Open
The twist-bend nematic liquid crystal phase is a three-dimensional fluid in which achiral bent molecules spontaneously form an orientationally ordered, macroscopically chiral, heliconical winding of a ten nanometer-scale pitch in the absen…
View article: Calorimetric evidence for the existence of an intermediate phase between the ferroelectric nematic phase and the nematic phase in the liquid crystal RM734
Calorimetric evidence for the existence of an intermediate phase between the ferroelectric nematic phase and the nematic phase in the liquid crystal RM734 Open
The idea that rod-like molecules possessing an electric dipole moment could exhibit a ferroelectric nematic phase was suggested more than a century ago. However, only recently such a phase has been reported for two quite different liquid c…
View article: How smectic-A and smectic-C liquid crystals resolve confinement-induced frustration in spherical shells
How smectic-A and smectic-C liquid crystals resolve confinement-induced frustration in spherical shells Open
The geometrical frustration known to generate a spherical lune texture in SmA shells is largely relieved in SmC, thanks to the freedom of the director to rotate on the tilt cone. SmC shell lunes are thus twice as wide and half as many.
View article: Thermotropic reentrant isotropy and antiferroelectricity in the ferroelectric nematic realm: Comparing RM734 and DIO
Thermotropic reentrant isotropy and antiferroelectricity in the ferroelectric nematic realm: Comparing RM734 and DIO Open
The current intense study of ferroelectric nematic liquid crystals was initiated by the observation of the same ferroelectric nematic phase in two independently discovered organic rod-shaped mesogenic compounds, RM734 and DIO. We recently …
View article: Thermotropic reentrant isotropy and antiferroelectricity in the ferroelectric nematic material RM734
Thermotropic reentrant isotropy and antiferroelectricity in the ferroelectric nematic material RM734 Open
We report a transition from the ferroelectric nematic liquid crystal ($N_F$) phase to a lower-temperature, antiferroelectric fluid phase having reentrant isotropic symmetry ($I_A$), in the liquid crystal compound RM734 doped with small con…
View article: The smectic Z <sub>A</sub> phase: Antiferroelectric smectic order as a prelude to the ferroelectric nematic
The smectic Z <sub>A</sub> phase: Antiferroelectric smectic order as a prelude to the ferroelectric nematic Open
We have structurally characterized the liquid crystal (LC) phase that can appear as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to the almost perfectly polar-ordered ferroele…
View article: Observation of a uniaxial ferroelectric smectic A phase
Observation of a uniaxial ferroelectric smectic A phase Open
We report the observation of the smectic A F , a liquid crystal phase of the ferroelectric nematic realm. The smectic A F is a phase of small polar, rod-shaped molecules that form two-dimensional fluid layers spaced by approximately the me…
View article: Understanding and Manipulating Helical Nanofilaments in Binary Systems with Achiral Dopants
Understanding and Manipulating Helical Nanofilaments in Binary Systems with Achiral Dopants Open
Here, we report the relationship between helical pitch of the helical nanofilament (HNF) phase formed by bent-core molecule NOBOW and the concentration of achiral dopants 5CB and octane, using linearly polarized resonant soft X-ray scatter…
View article: Ideal mixing of paraelectric and ferroelectric nematic phases in liquid crystals of distinct molecular species
Ideal mixing of paraelectric and ferroelectric nematic phases in liquid crystals of distinct molecular species Open
The organic mesogens RM734 and DIO are members of separate molecular families featuring distinct molecular structures. These families, at the present time, are the only ones known to exhibit a ferroelectric nematic liquid crystal (LC) phas…
View article: Precise orientation control of a liquid crystal organic semiconductor via anisotropic surface treatment
Precise orientation control of a liquid crystal organic semiconductor via anisotropic surface treatment Open
We report a three-dimensional (3D) molecular orientation control of a liquid crystal organic semiconductor (LC-OSC) based on the long-range ordering characteristic of an LC material. To this end, a synthetic LC-OSC molecule, MeOPh-BTBT-C8,…
View article: Correction: Surface alignment of ferroelectric nematic liquid crystals
Correction: Surface alignment of ferroelectric nematic liquid crystals Open
Correction for ‘Surface alignment of ferroelectric nematic liquid crystals’ by Federico Caimi et al. , Soft Matter , 2021, 17 , 8130–8139, https://doi.org/10.1039/D1SM00734C.
View article: Antiferroelectric Smectic Ordering as a Prelude to the Ferroelectric Nematic:Introducing the Smectic $Z_A$ Phase
Antiferroelectric Smectic Ordering as a Prelude to the Ferroelectric Nematic:Introducing the Smectic $Z_A$ Phase Open
We have structurally characterized the liquid crystal phase that appears as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to the almost perfectly polar-ordered ferroelectric ne…
View article: Ideal Mixing of Paraelectric and Ferroelectric Nematic Phases in Liquid Crystals of Distinct Molecular Species
Ideal Mixing of Paraelectric and Ferroelectric Nematic Phases in Liquid Crystals of Distinct Molecular Species Open
The organic mesogens RM734 and DIO are members of separate molecular families featuring distinct molecular structures. These families, at the present time, are the only ones known to exhibit a ferroelectric nematic liquid crystal (LC) phas…
View article: Polar in-plane surface orientation of a ferroelectric nematic liquid crystal: Polar monodomains and twisted state electro-optics
Polar in-plane surface orientation of a ferroelectric nematic liquid crystal: Polar monodomains and twisted state electro-optics Open
Significance The devices of the portable computing revolution are being made possible by nematic liquid crystal display (LCD) technology. The optical changes viewed in a dynamic LCD image are based on reorienting molecules by coupling elec…
View article: Polar In-Plane Surface Orientation of a Ferroelectric Nematic Liquid Crystal: Field-Free Electrical Poling and Twisted State Electro-Optics
Polar In-Plane Surface Orientation of a Ferroelectric Nematic Liquid Crystal: Field-Free Electrical Poling and Twisted State Electro-Optics Open
We demonstrate that the surface polarity of a ferroelectric nematic can be configured to generate vectorial control of the orientation of its bulk polarization field. The contact between a surface with in-plane polarity and a ferroelectric…
View article: First-principles experimental demonstration of ferroelectricity in a thermotropic nematic liquid crystal: Polar domains and striking electro-optics
First-principles experimental demonstration of ferroelectricity in a thermotropic nematic liquid crystal: Polar domains and striking electro-optics Open
We report the experimental determination of the structure and response to applied electric field of the lower-temperature nematic phase of the previously reported calamitic compound 4-[(4-nitrophenoxy)carbonyl]phenyl2,4-dimethoxybenzoate (…
View article: Frontispiece: Nanoconfinement of the Low‐Temperature Dark Conglomerate: Structural Control from Focal Conics to Helical Nanofilaments
Frontispiece: Nanoconfinement of the Low‐Temperature Dark Conglomerate: Structural Control from Focal Conics to Helical Nanofilaments Open
Interesting things happen in smectic (lamellar) liquid-crystal phases dominated by a tendency for saddle-splay deformation of the layers. The two main ways this tendency is expressed is with the formation of either “dark conglomerate” or “…
View article: Distinct differences in the nanoscale behaviors of the twist–bend liquid crystal phase of a flexible linear trimer and homologous dimer
Distinct differences in the nanoscale behaviors of the twist–bend liquid crystal phase of a flexible linear trimer and homologous dimer Open
Significance The twist–bend (TB) liquid crystal phase is the newest nematic phase, having only been identified in 2011. Still, there are many outstanding mysteries about the nature of its nanoscale organization and behavior. We elucidate h…
View article: Chiral Incommensurate Helical Phase in a Smectic of Achiral Bent-Core Mesogens
Chiral Incommensurate Helical Phase in a Smectic of Achiral Bent-Core Mesogens Open
An achiral, bent-core mesogen forms several tilted smectic liquid crystal phases, including a nonpolar, achiral de Vries smectic A which transitions to a chiral, ferroelectric state in applied electric fields above a threshold. At lower te…
View article: Highly Oriented Liquid Crystal Semiconductor for Organic Field-Effect Transistors
Highly Oriented Liquid Crystal Semiconductor for Organic Field-Effect Transistors Open
We report a mesogenic compound which introduces nematic liquid crystal (LC) ordering into the benzothienobenzothiophene (BTBT) family of LCs, creating a new class of LC semiconducting materials which respond in a facile way to anisotropic …
View article: Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase
Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase Open
We produced controlled heliconical structures of a twist-bend nematic (NTB) liquid-crystal (LC) phase in nanoconfinement in a porous anodic aluminium oxide (AAO) film. The structural parameters of the NTB phase such a…
View article: New SmAPF Mesogens Designed for Analog Electrooptics Applications
New SmAPF Mesogens Designed for Analog Electrooptics Applications Open
We have previously reported the first realization of an orthogonal ferroelectric bent-core SmAPF phase by directed design in mesogens with a single tricarbosilane-terminated alkoxy tail. Given the potentially useful electrooptic properties…
View article: Distinct differences in the nanoscale behaviors of the twist-bend liquid crystal phase of a flexible linear trimer and homologous dimer
Distinct differences in the nanoscale behaviors of the twist-bend liquid crystal phase of a flexible linear trimer and homologous dimer Open
We synthesized the liquid crystal dimer and trimer members of a series of flexible linear oligomers and characterized their microscopic and nanoscopic properties using resonant soft x-ray scattering and a number of other experimental techn…
View article: Distinct differences in the nanoscale behaviors of the twist-bend liquid\n crystal phase of a flexible linear trimer and homologous dimer
Distinct differences in the nanoscale behaviors of the twist-bend liquid\n crystal phase of a flexible linear trimer and homologous dimer Open
We synthesized the liquid crystal dimer and trimer members of a series of\nflexible linear oligomers and characterized their microscopic and nanoscopic\nproperties using resonant soft x-ray scattering and a number of other\nexperimental te…
View article: Double-Helical Tiled Chain Structure of the Twist-Bend Liquid Crystal phase in CB7CB
Double-Helical Tiled Chain Structure of the Twist-Bend Liquid Crystal phase in CB7CB Open
The twist-bend nematic liquid crystal phase is a three-dimensional fluid in which achiral bent molecules spontaneously form an orientationally ordered macroscopically chiral heliconical winding of molecular scale pitch, in absence of posit…
View article: Structural transitions and guest/host complexing of liquid crystal helical nanofilaments induced by nanoconfinement
Structural transitions and guest/host complexing of liquid crystal helical nanofilaments induced by nanoconfinement Open
A perfectly aligned liquid crystal phase can be achieved by an interaction with helical nanofilament under nanoconfinement.
View article: Aggregation-driven, re-entrant isotropic phase in a smectic liquid crystal material
Aggregation-driven, re-entrant isotropic phase in a smectic liquid crystal material Open
An azobenzene-core chiral mesogen designed for a photoactive ferroelectric liquid crystal system with switchable polarisation displays a highly unusual phase sequence, with a re-entrant, optically isotropic, fluid phase found below smectic…
View article: Airflow-aligned helical nanofilament (B4) phase in topographic confinement
Airflow-aligned helical nanofilament (B4) phase in topographic confinement Open