This title appears in the Scientific Report :
2018
Please use the identifier:
http://dx.doi.org/10.1126/sciadv.aao7086 in citations.
Please use the identifier: http://hdl.handle.net/2128/18027 in citations.
Time-resolved structural evolution during the collapse of responsive hydrogels: The microgel-to-particle transition
Time-resolved structural evolution during the collapse of responsive hydrogels: The microgel-to-particle transition
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 defi...
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Personal Name(s): | Keidel, Rico (Corresponding author) |
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Ghavami, Ali / Lugo, Dersy M. / Lotze, Gudrun / Virtanen, Otto / Beumers, Peter / Pedersen, Jan Skov / Bardow, Andre / Winkler, Roland G. (Corresponding author) / Richtering, Walter (Corresponding author) | |
Contributing Institute: |
Theorie der Weichen Materie und Biophysik; IAS-2 JARA-SOFT; JARA-SOFT Theorie der Weichen Materie und Biophysik; ICS-2 |
Published in: | Science advances, 4 (2018) 4, S. eaao7086 |
Imprint: |
Washington, DC [u.a.]
Assoc.
2018
|
DOI: |
10.1126/sciadv.aao7086 |
PubMed ID: |
29740608 |
Document Type: |
Journal Article |
Research Program: |
Functional Macromolecules and Complexes |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/18027 in citations.
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. |