Journal Article

FZJ-2018-01484

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Time-resolved structural evolution during the collapse of responsive hydrogels: The microgel-to-particle transition

Keidel, R. (Corresponding author) ; Ghavami, A.FZJ* ; Lugo, D. M. ; Lotze, G. ; Virtanen, O. ; Beumers, P. ; Pedersen, J. S. ; Bardow, A.FZJ* ; Winkler, R. G. (Corresponding author)FZJ* ; Richtering, W. (Corresponding author)Extern*

2018
Assoc. Washington, DC [u.a.]

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Please use a persistent id in citations: http://hdl.handle.net/2128/18027  doi:10.1126/sciadv.aao7086

Abstract: Adaptive hydrogels, often termed smart materials, are macromolecules whose structure adjusts to external stimuli. Responsive micro- and nanogels are particularly interesting because the small length scale enables very fast response times. Chemical cross-links provide topological constraints and define the three-dimensional structure of the microgels, whereas their porous structure permits fast mass transfer, enabling very rapid structural adaption of the microgel to the environment. The change of microgel structure involves a unique transition from a flexible, swollen finite-size macromolecular network, characterized by a fuzzy surface, to a colloidal particle with homogeneous density and a sharp surface. In this contribution, we determine, for the first time, the structural evolution during the microgel-to-particle transition. Time-resolved small-angle x-ray scattering experiments and computer simulations unambiguously reveal a two-stage process: In a first, very fast process, collapsed clusters form at the periphery, leading to an intermediate, hollowish core-shell structure that slowly transforms to a globule. This structural evolution is independent of the type of stimulus and thus applies to instantaneous transitions as in a temperature jump or to slower stimuli that rely on the uptake of active molecules from and/or exchange with the environment. The fast transitions of size and shape provide unique opportunities for various applications as, for example, in uptake and release, catalysis, or sensing.

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Contributing Institute(s):

1. Theorie der Weichen Materie und Biophysik (IAS-2)
2. Theorie der Weichen Materie und Biophysik (ICS-2)
3. JARA-SOFT (JARA-SOFT)

Research Program(s):

1. 551 - Functional Macromolecules and Complexes (POF3-551) (POF3-551)

Appears in the scientific report 2018

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Database coverage:
; ; ; ; DOAJ Seal ; Emerging Sources Citation Index ; NCBI Molecular Biology Database ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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