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@INPROCEEDINGS{Kang:911211,
author = {Kang, Kyongok},
title = {{L}ow {I}onic {S}trength {E}quilibria of {C}harged
{DNA}-{R}ods and {T}heir {B}ulk {R}esponse to {S}hear
{F}low},
reportid = {FZJ-2022-04516},
year = {2022},
abstract = {At sufficiently low ionic strengths (below 1 mM Tris/HCl
buffer), long and thin, highly charged colloidal rods
(fd-virus particles) exhibit various chiral-mesophases
consisting of different orientations of chiral-nematic
domains and helical domains, well above the
isotropic-nematic coexistence concentration [1,2]. In
addition, a glass transition has been observed, where the
particle dynamics within nematic domains as well as the
dynamics of the domain texture are dynamically arrested at
the same glass-transition concentration [3-5]. Such a glass
transition only occurs for sufficiently low ionic strengths,
and is therefore attributed to caging of particles due to
relatively long-ranged electrostatic interactions. After a
short discussion of low ionic strength equilibria of
suspensions of charged DNA-Rods (fd), experiments on the
bulk response of such rod-glasses of charged DNA-rods to
shear flow will be presented. Depending on the applied shear
rate, various inhomogeneous flow profiles are observed,
where the flow velocity varies along the gradient direction
and/or the vorticity direction. Fracture and plug flow as
observed at low shear rates, gradient-shear-banding at
intermediate shear rates, and a linear profile at
sufficiently high shear rates [6]. There is a shear
rate-rate range where these flow profiles coexist with
Taylor vorticity bands [6-8]. Plug flow is most probably due
to the brittle nature of the sample, consisting of elastic
glassy nematic domains. The mechanism for
gradient-shear-banding in these systems with a soft,
long-ranged repulsive inter-particle potential, is shown to
be due to the classic gradient-banding scenario related to
strong shear-thinning behaviour [7]. 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 [7]. References: [1] Scientific
Reports 11, 3472 (2021), [2] J. Phys. Commun, 6, 015001
(2022) [3] Phys. Rev. Lett. 110, 015901 (2013) [4] Soft
Matter 9, 4401 (2013) [5] Soft Matter 10, 3311 (2014) [6]
Phys. Rev. Fluids 2, 043301 (2017) [7] J. Rheol. 66, 2,
March 1st (2022) [8] J. Phys. Commun. 5, 045011 (2021)},
month = {Sep},
date = {2022-09-19},
organization = {Int. Soft Matter Conference 2022,
Poznan (Poland), 19 Sep 2022 - 23 Sep
2022},
subtyp = {After Call},
cin = {IBI-4},
cid = {I:(DE-Juel1)IBI-4-20200312},
pnm = {5241 - Molecular Information Processing in Cellular Systems
(POF4-524)},
pid = {G:(DE-HGF)POF4-5241},
typ = {PUB:(DE-HGF)6},
url = {https://juser.fz-juelich.de/record/911211},
}