By means of a molecular model, we examine hybrid nematic films with antagonistic anchoring angles where one of the surfaces is in the strong anchoring regime. If anchoring at the other surface is weak, and in the absence of wetting by the isotropic phase, the anchoring transition may interact with the capillary isotropic-nematic transition. For general anchoring conditions on this surface we confirm the existence of the steplike biaxial phase and the associated transition to the linear constant-tilt-rotation, configuration. The steplike phase is connected with the bulk isotropic phase for increasing film thickness so that the latter transition is to be interpreted as the capillary isotropic-nematic transition in a hybrid film.
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http://dx.doi.org/10.1103/PhysRevE.79.011712 | DOI Listing |
Adv Sci (Weinh)
January 2025
South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, China.
High birefringence nematic liquid crystals are particularly demanded for adaptive optics applications in the infrared spectrum because it enable a thinner cell gap for achieving fast response time and improved diffraction efficiency. The emerging ferroelectric nematic liquid crystals have attracted widespread interest in soft matter due to their unique combination of ferroelectricity and fluidity. However, the birefringence, which is one of the most important optical parameters in electro-optic devices, is not large enough (<0.
View Article and Find Full Text PDFChemistry
December 2024
Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada.
The creation of multicomponent materials with desired properties and functions is a challenge of modern materials chemistry. Chiral nematic mesoporous organosilicas have iridescent properties that make them attractive for decoration and sensing. In this paper, we demonstrate the chemical functionalization of chiral nematic mesoporous organosilica films with cyclodextrin.
View Article and Find Full Text PDFPNAS Nexus
December 2024
Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Ferroelectric nematic (N) liquid crystals present a compelling platform for exploring topological defects in polar fields, while their structural properties can be significantly altered by ionic doping. In this study, we demonstrate that doping the ferroelectric nematic material RM734 with cationic polymers enables the formation of polymeric micelles that connect pairs of half-integer topological defects. Polarizing optical microscopy reveals that these string defects exhibit butterfly textures, featured with a 2D polarization field divided by Néel-type kink walls into domains exhibiting either uniform polarization or negative splay and bend deformations.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Ferroelectric nematic liquid crystals are polar fluids characterized by microscopic orientational ordering and macroscopic spontaneous polarizations. Within these fluids, domain walls that separate regions of different polarizations are ubiquitous. We demonstrate that the π walls in films of the polar fluids consist of twin half-integer surface disclinations spaced horizontally, enclosing a subdomain where the polarization exhibits left- or right-handed π twists across the film.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Department of Physics, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Bilbao, Spain.
Following the groundbreaking discovery of the ferroelectric nematic liquid crystal phase (N_{F}), a series of closely-related new polar phases have also been found. An especially interesting one is the ferroelectric smectic A phase (SmA_{F}) with spontaneous polarization along the layer normal observed in a few materials of the N_{F} realm. Here, we present a mean-field molecular model that successfully captures the rich phase diagrams experimentally observed in the literature in terms of two parameters.
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