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| Home > Publications database > Low Ionic Strength Equilibria and Non-equilibrium Phase Transitions of Charged Colloidal Rods (DNA-viruses) |
| Talk (non-conference) (Invited) | FZJ-2024-06341 |
2024
Abstract: At sufficiently low ionic strengths (below 1 mM Tris/HCl buffer), long and thin, highly charged colloidal rods (DNA-viruses) exhibit various chiral-mesophases consisting of different orientations of chiral-nematic and helical domains, well above the isotropic-nematic coexistence concentration. Both non-equilibrium (in electric-field and shear flow) [1-3] and equilibrium phase behaviour [4-7] are presented for the concentrated suspension of charged DNA-viruses, which is a good model system of charged colloidal rods (DNA-rods) to predict the phase transitions; from the nematic-to-chiral nematic and other hierarchical chiral-mesophases (X-pattern and helical domains) to the glass states, in an increase of the rod-concentration [4-6]. In last 2 decades, several instrumentations and methods are also developed to characterize both signal-and image-processing (under external fields) in access multiple phases and various transitions, dynamics, and kinetics of the interacting charged DNA-rods. In this talk, experiments on both equilibrium and the field-induced phase transition, as well shear response of the glass state will be discussed. The (structural) glass transition occurs well within the full chiral-nematic state, where the particle dynamics and the orientation texture dynamics are simultaneously arrested, at the same concentration. The glass is also found to exhibit several types of non-uniform flow profiles, depending on the externally applied shear rate: At low shear rates plug flow is observed and at intermediate shear rates gradient-banded flow profiles are found. At high shear rates the glass is melted, leading to a linear flow profile. Finally, as one of interesting findings for chiral-mesophases, is a “chiral-glass”, driven by the replica symmetry breaking (RSB), determined by both real- and Fourier-space [6], kept between the two “replicas” of larger chiral-nematic domain (at a lower concentration) and the “helical-domains” (at a higher concentration) of charged DNA-rods [7]. As will be shown, there is a subtle interplay between the stress originating from inter-particle interactions within the domains and the texture stress due to inter-domain interactions.References:[1] K. Kang and J.K.G. Dhont, “An electric-field induced dynamical state in dispersions of highly charged colloidal rods: Comparison of experiment and theory”, Colloid. Polym. Sci. 293, 3325-3336, 2015: Soft Matter 10, 3311 (2014). [2] K. Kang, “Response of shear in bulk orientations of charged DNA rods: Taylor- and Gradient-banding”, J. Phys. Commun, 5, 045011, 2021. [3] D. Parisi, D. Vlassopoulos, H. Kriegs, J. K. G. Dhont, and K. Kang, “Underlying mechanism of shear-banding in soft glasses of charged colloidal rods with orientational domains”, Journal of Rheology 66, 365, 2022: Phys. Rev. Fluids 2, 043301 (2017). [4] K. Kang and J. K. G. Dhont, “Glass transition in suspensions of charged rods: Structural arrest and texture dynamics”, Phys. Rev. Lett. 110, 015901, 2013: K. Kang, “Glass transition of repulsive charged rods (fd-viruses)”, Soft Matter, 10, 3311-3324, 2014: Soft Matter 9, 4401 (2013). [5] K. Kang, “Equilibrium phase diagram and thermal responses of charged DNA-virus rod-suspensions at low ionic strengths”, Sci. Rep. 11: 3472, 2021. [6] K. Kang, “Chiral glass of charged DNA rods, Cavity loops”, J. Phys. Commun, 5, 065001, 2021. [7] K. Kang, “Characterization of orientation correlation kinetics: chiral-mesophase domains in suspensions charged DNA-rods”, J. Phys. Commun, 6, 015001, 2022.
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