Abstract
This article is a comprehensive overview of the ongoing research of the author on charged colloidal rods out of equilibrium, under external electric fields and at high concentrations around the glass transition. The suspensions of fd-virus particles are used as a model system for charged colloidal rods, which exhibit several disorder-order (and liquid-crystalline) phase transitions. When a low AC electric field is applied to suspensions in isotropic-nematic coexistence concentration, with frequencies that are sufficiently low to polarize the electric double layer and the layer of condensed ions, various phases/states are induced: a chiral nematic, a dynamical state where nematic domains persistently melt and form, and a uniform homeotropic phase. A point in the field-amplitude versus frequency diagram, where various transitions lines meet, can be identified as a non-equilibrium critical point. Without an electric field, at high concentrations of charged fd-rods, various self-assembled orientation textures are found beyond the isotropic-nematic coexistence regions, and a glass transition is observed on approach and within the glass state that are probed. The presented system exhibits transient behaviors of repulsive glasses and slow dynamics out of equilibrium.
Highlights
This paper presents results on the non-equilibrium behavior of suspensions of charged colloidal rods under low-frequency external AC electric fields, as well as at relatively high concentrations where a glass state is formed
As a model system of charged colloidal rods, suspensions of charged fibrous viruses are used at a low ionic strength corresponding to a Tris/HCl buffer solution of 0.16 mM where the Debye length is 27 nm
There is a point in the phase/state diagram in Figure 2 where several transition lines meet, seemingly similar to a critical point in equilibrium phase diagrams, which can be distinguished as low-and highfrequency electric fields [2]: at low-frequency, two sharp phase transitions of entering the chiral-nematic N*phase and dynamical states, relatively at high frequencies, above a frequency of about 400 Hz - 1 kHz, only homeotropically aligned H-phase is stabilized, along the electric field direction
Summary
This paper presents results on the non-equilibrium behavior of suspensions of charged colloidal rods under low-frequency external AC electric fields, as well as at relatively high concentrations where a glass state is formed. Various phases/states are induced by an external electric field, for low frequencies less than a few kHz [1] [2]. The polarization of the layer of condensed ions is accompanied by a cyclic association/dissociation of these ions These phenomena lead to several field-induced phases/states in suspensions that are in isotropic-nematic coexistence concentration without the external field. Dynamic light scattering experiments will be discussed which reveal particle arrest, while image-time correlation shows freezing of the orientation texture dynamics, at the same concentration This glass transition is attributed to particle caging due to strongly overlapping electric double layers. Only reference is made to the papers where the original work is described, in which the many references that are relevant to these topics can be found
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
