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Interpenetration of polymeric microgels at ultrahigh densities

Mohanty, Priti S. LU ; Nöjd, Sofi LU ; van Gruijthuijsen, Kitty; Crassous, Jerome LU ; Obiols-Rabasa, Marc LU ; Schweins, Ralf; Stradner, Anna LU and Schurtenberger, Peter LU (2017) In Scientific Reports 7(1).
Abstract

Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions φ eff above close packing (φ cp ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above φcp using the zero average contrast method in... (More)

Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions φ eff above close packing (φ cp ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above φcp using the zero average contrast method in small-angle neutron scattering. We complement these experiments with measurements of the average interparticle distances using small-angle X-ray scattering, and a determination of the glass transition using dynamic light scattering. This allows us to unambiguously decouple interaction effects from density-dependent variations of the particle size and shape at all values of φeff . We demonstrate that the microgels used in this study significantly interpenetrate and thus change their size and shape only marginally even for φeff > φ cp, a finding that may require changes in the interpretation of a number of previously published studies on the structural and dynamic properties of dense soft particle systems.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Scientific Reports
volume
7
issue
1
publisher
Nature Publishing Group
external identifiers
  • scopus:85018777569
  • wos:000400492400018
ISSN
2045-2322
DOI
10.1038/s41598-017-01471-3
language
English
LU publication?
yes
id
a4b65a0b-dcc1-4331-8a09-3802a2abc507
date added to LUP
2017-05-23 09:45:16
date last changed
2017-09-18 11:36:43
@article{a4b65a0b-dcc1-4331-8a09-3802a2abc507,
  abstract     = {<p>Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a <sub>s</sub> can be smaller than the initial unperturbed particle diameter σ <sub>0</sub>, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions φ <sub>eff</sub> above close packing (φ <sub>cp</sub> ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above φ<sub>cp</sub> using the zero average contrast method in small-angle neutron scattering. We complement these experiments with measurements of the average interparticle distances using small-angle X-ray scattering, and a determination of the glass transition using dynamic light scattering. This allows us to unambiguously decouple interaction effects from density-dependent variations of the particle size and shape at all values of φ<sub>eff</sub> . We demonstrate that the microgels used in this study significantly interpenetrate and thus change their size and shape only marginally even for φ<sub>eff</sub> &gt; φ <sub>cp</sub>, a finding that may require changes in the interpretation of a number of previously published studies on the structural and dynamic properties of dense soft particle systems.</p>},
  articleno    = {1487},
  author       = {Mohanty, Priti S. and Nöjd, Sofi and van Gruijthuijsen, Kitty and Crassous, Jerome and Obiols-Rabasa, Marc and Schweins, Ralf and Stradner, Anna and Schurtenberger, Peter},
  issn         = {2045-2322},
  language     = {eng},
  month        = {12},
  number       = {1},
  publisher    = {Nature Publishing Group},
  series       = {Scientific Reports},
  title        = {Interpenetration of polymeric microgels at ultrahigh densities},
  url          = {http://dx.doi.org/10.1038/s41598-017-01471-3},
  volume       = {7},
  year         = {2017},
}