Related Experiment Video
Updated: Jun 22, 2026
10:08
Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy
Published on: October 24, 2017
Effective shape and phase behavior of short charged rods
Eelco Eggen1, Marjolein Dijkstra, René van Roij
1Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
Summary
We calculated the effective dimensions of charged rods in solution, revealing distinct liquid crystalline and plastic crystal phases based on charge and screening levels. This provides insights into self-assembling materials.
Area of Science:
- Physical Chemistry
- Materials Science
- Soft Matter Physics
Background:
- Understanding the phase behavior of charged colloidal systems is crucial for designing novel materials.
- Charged rod-like particles exhibit complex interactions influenced by electrostatic forces and solvent screening.
Purpose of the Study:
- To calculate the orientation-dependent second virial coefficient for short charged rods.
- To determine the effective dimensions (length and diameter) of these rods.
- To map the phase diagram of charged rods based on varying charge and screening lengths.
Main Methods:
- Explicit calculation of the orientation-dependent second virial coefficient.
- Modeling rod-rod interactions using hard-core and screened-Coulomb potentials.
- Averaging the second virial coefficient to obtain effective rod dimensions.
- Phase diagram determination based on effective dimensions.
Main Results:
- The study distinguishes between low-charge/strong-screening and high-charge/weak-screening regimes.
- A liquid crystalline nematic and smectic phase is observed in the low-charge/strong-screening regime.
- A plastic crystal phase is identified in the high-charge/weak-screening regime.
Conclusions:
- The effective dimensions of charged rods are strongly dependent on charge and screening length.
- The phase behavior of charged rods is predictable using these effective dimensions.
- This work provides a theoretical framework for understanding and predicting the self-assembly of charged rod-like systems.
Related Concept Videos
01:16Equipotential Surfaces and Conductors
For a conductor in which all charges are at rest, the conductor's surface is equipotential. The electric field is always perpendicular to equipotential surfaces. Therefore, in a conductor with static charges, the electric field just outside the conductor is always perpendicular to the conductor's surface. Any tangential component of the electric field will cause charges to move inside the conductor, which will violate the electrostatic nature of the system. In an electrostatic situation, if a...
01:19Electric Field of a Continuous Line Charge
In physics, symmetry in a system means that something in the considered system remains unchanged due to a specific operation to which it is subjected. For example, consider a horizontal square. The square looks the same if its right and left sides are interchanged. Hence, it is symmetric under a right-left interchange.
In calculations of electric fields, symmetry is of great use. For example, while calculating electric fields of continuous charge distributions.
Consider a line element with a...
In calculations of electric fields, symmetry is of great use. For example, while calculating electric fields of continuous charge distributions.
Consider a line element with a...
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
01:15Charging Conductors By Induction
The Earth is a good conductor of electricity, and it is so big that it can be considered an infinite source or sink of charges. It can easily exchange charges with any matter.
Generally, conductors like metals do not allow any excess charge to be present on them. Any excess charge added to metals easily flows away, for example, when a metal is placed on the Earth. This process is called earthing.
However, conductors can be charged by a process called induction. For example, consider charging a...
Generally, conductors like metals do not allow any excess charge to be present on them. Any excess charge added to metals easily flows away, for example, when a metal is placed on the Earth. This process is called earthing.
However, conductors can be charged by a process called induction. For example, consider charging a...
01:22Motional Emf
Magnetic flux depends on three factors: the strength of the magnetic field, the area through which the field lines pass, and the field's orientation with respect to the surface area. If any of these quantities vary, a corresponding variation in magnetic flux occurs. If the area through which the magnetic field lines are passing changes, then the magnetic flux also changes. This change in the area can be of two types: the flux through the rectangular loop increases as it moves into the magnetic...
01:23Electric Field of a Charged Disk
The simplest case of a surface charge distribution is the uniformly charged disk. Calculating its electric field also helps us calculate the electric field of a large plane of charge.
The system's symmetry is in the cylindrical directions across the plane of the charge. As a result, the electric fields created by various surface charge elements nullify each other in the direction parallel to the surface. Thereby, the resulting electric field is perpendicular to the plane. Since the disk is...
The system's symmetry is in the cylindrical directions across the plane of the charge. As a result, the electric fields created by various surface charge elements nullify each other in the direction parallel to the surface. Thereby, the resulting electric field is perpendicular to the plane. Since the disk is...