Related Experiment Video
Updated: Jul 15, 2026
12:04
Microfluidic Preparation of Liquid Crystalline Elastomer Actuators
Published on: May 20, 2018
Structure-flexoelastic properties of bimesogenic liquid crystals
S M Morris1, M J Clarke, A E Blatch
1Centre of Molecular Materials for Photonics and Electronics, Electrical Engineering Division, Department of Engineering, Cambridge University, 9 J J Thomson Avenue, Cambridge CB3 0FA, United Kingdom. smm56@cam.ac.uk
Summary
The flexoelectric and viscoelastic properties of bimesogens were studied. Molecular structure modifications, like bend angle and dipole moment, influenced these properties, showing an odd-even effect related to molecular spacing.
Area of Science:
- Materials Science
- Liquid Crystals
- Organic Chemistry
Background:
- Flexoelectricity in liquid crystals is crucial for display technologies.
- Understanding structure-property relationships in bimesogens is key to optimizing material performance.
- The flexoelastic ratio (e/K) and effective flexoelectric coefficient (e) are important parameters.
Purpose of the Study:
- To investigate the flexoelastic and viscoelastic ratios of bimesogen compounds.
- To determine how molecular structure variations (bend angle, dipole moment, length) affect these ratios.
- To explore the influence of molecular spacing (odd-even effect) on flexoelectric properties.
Main Methods:
- Indirect measurement of flexoelastic and viscoelastic ratios via flexoelectro-optic response in the chiral nematic phase.
- Systematic variation of molecular structure in bimesogens, including homologous series with varying aliphatic spacer lengths (n).
- Modification of mesogenic units and aliphatic spacer linkages to alter dipole moments.
Main Results:
- A distinct odd-even effect was observed in the flexoelectric ratio (e/K) and effective flexoelectric coefficient (e) based on the aliphatic spacer length (n).
- Odd values of n (odd-spaced bimesogens) showed greater flexoelectric ratios compared to even values.
- Increased bend angle and transverse dipole moment were correlated with higher flexoelectric ratios, particularly in odd-spaced bimesogens with larger transverse dipole moments.
Conclusions:
- Molecular structure, specifically bend angle and transverse dipole moment, significantly impacts the flexoelectric properties of bimesogens.
- The observed odd-even effect in flexoelectric properties is attributed to variations in molecular geometry and dipole distribution.
- Tailoring molecular design of bimesogens can optimize their flexoelectric response for potential applications.
Related Concept Videos
01:19Members Made of Elastoplastic Material
The behavior of elastoplastic materials under bending stresses, particularly in structural members with rectangular cross-sections, is crucial for predicting material responses and understanding failure modes. Initially, when a bending moment is applied, the stress distribution across the section follows Hooke's Law and is linear and elastic. This distribution means the stress increases from the neutral axis to the maximum at the outer fibers, up to the elastic limit.
As the bending moment...
As the bending moment...
01:15Mechanisms of Membrane-bending
The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
01:28Classification and Mechanical Properties of Synthetic Polymers
Synthetic polymers are classified as elastomers, fibers, or plastics based on their crystallinity. Crystallinity, the degree of long-range order in the solid state, influences the mechanical properties (stretching or contracting) of elastomers. Elastomers are flexible polymers that can expand or contract easily upon the application of an external force. They have numerous crosslinks that pull them back into their original shape when stress is removed. Silicones, for instance, are highly elastic...
01:21Plastic Behavior
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and reloaded.
01:18Residual Stresses in Bending
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...