Abstract
Colloidal particles dispersed in nematic liquid crystals are aligned along the orientation that minimizes the elastic free energy. Through applying an electric field to a nematic colloidal system, the orientation of the director can change. Consequently, colloidal particles realign to minimize the total free energy, which is the sum of the elastic and electric free energies. Herein, we demonstrate that if the preferred rotation directions given by the electric and elastic free energies are different during realignment, the rotation direction of the particle can be controlled by how we apply the electric field. When the strength of the electric field gradually increases, the particles rotate in the same direction as the rotation of the director. However, when a sufficiently high electric field is suddenly applied, the particles rotate in the opposite direction. In this study, we analyzed the effect of free energy on the bidirectional rotation behavior of the particles using a theoretical model. This study provides an effective approach to control the rotational behavior of colloidal particles over a wide-angle range between two orientational local minima.
Highlights
Colloidal particles dispersed in nematic liquid crystals are aligned along the orientation that minimizes the elastic free energy
When colloidal particles are dispersed in nematic liquid crystals (NLCs), their surfaces interact with the director
Anisotropic particles dispersed in NLCs are aligned in a particular orientation because of their interaction with the director
Summary
Colloidal particles dispersed in nematic liquid crystals are aligned along the orientation that minimizes the elastic free energy. The direction of rod-shaped colloidal particles that are dispersed in NLCs can be controlled by modifying the anchoring and elastic properties of NLCs. When colloidal particles are dispersed in NLCs, their surfaces interact with the director. Particles have a preferred direction in NLCs. the orientational behavior of the particles can be induced by controlling the surface condition of the confining cell or exerting external stimuli such as magnetic and electric fields. Another study confirmed that the alignment of rod-shaped particles depends on their surface condition, i.e., when the particles have an axial or homeotropic anchoring condition, they align in the direction parallel or perpendicular to the far-field director, respectively[23]. The precise static and dynamic properties of individual particles have been investigated by modifying the strength of the Scientific Reports | (2020) 10:18650
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