Colloid and Polymer Science

, Volume 295, Issue 8, pp 1371–1381 | Cite as

Diffusion of rigid nanoparticles in crowded polymer-network hydrogels: dominance of segmental density over crosslinking density

  • Stefan Walta
  • Fany Di Lorenzo
  • Kai Ma
  • Ulrich Wiesner
  • Walter Richtering
  • Sebastian Seiffert
Invited Article


Swollen polymer-network gels usually exhibit notable spatial inhomogeneity of their crosslinking density. The effect of this inhomogeneity on the permeability of the gel to small particles is of major importance in many applications such as those in analytical separation technology. To systematically address this effect, we mimic inhomogeneous polymer-network gels by dense-packed pastes of sub-micrometer-sized microgel building blocks with two distinctly different crosslinking degrees. The diffusive mobility of rigid nanoparticle tracers within these inhomogeneous pastes that contain purposely imparted densely and loosely cross-linked local domains is studied by spatially resolved dual-focus fluorescence correlation spectroscopy on a sub-micrometer length scale. The outcome of this investigation is that the sub-micrometer-scale tracer diffusivity of the tracers is not affected by the gel-matrix crosslinking density, and hence, also not by its spatial inhomogeneity. Instead, the tracer diffusion is dominantly hindered by the high density of polymer segments in the deswollen gel matrixes.


Microgels Hydrogels Tracer diffusion Crowding Fluorescence Fluorescence correlation spectroscopy C-dots 



K.M. and U.W. acknowledge support by the National Cancer Institute of the National Institutes of Health under Award Number U54CA199081.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

396_2017_4069_MOESM1_ESM.pdf (1.5 mb)
ESM 1 (PDF 1500 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  1. 1.RWTH Aachen UniversityInstitute of Physical Chemistry, JARA, Soft Matter ScienceAachenGermany
  2. 2.Physical-Chemistry DepartmentAdocia SALyonFrance
  3. 3.Department of Materials Science and EngineeringCornell UniversityIthacaUSA
  4. 4.Johannes Gutenberg-Universität MainzInstitute of Physical ChemistryMainzGermany

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