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Authors
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Hofmann, D.; Bittrich, E.; Appelhans, D.; Gaitzsch, J.
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Title
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Dynamic characteristics of redox- and thermoresponsive hydrogel films on the nanometer scale to compensate structure defects
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Date
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15.09.2025
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Number
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0
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Abstract
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The responsiveness of hydrogel films is influenced by network defects, particularly at the surface. It is hence required to study nanometer-thin hydrogel films as models for such surfaces, which is the topic of this work. These hydrogel films are designed to be dual-responsive. On the one hand, they are thermoresponsive, which is based on the LCST behavior of poly(N-isopropyl acrylamide) chains, and on the other hand, they are redox-responsive, due to the disulfide groups as partial cross-linking points. Stimuli-responsive swelling/deswelling is monitored by in situ ellipsometry. The response investigations show that structural defects from the synthesis can be successfully healed by just one initial redox cycle. The thickness values of the hydrogel films in the first redox cycle are unorthodox, but the gels respond as expected to the second and third redox cycles. The nanometer-thin films of PNiPAAm also behave unexpectedly to temperature switches right after their synthesis. Adding one redox cycle to release structural defects leads to reversible thermoresponsive behavior. In addition, the influence of both stimuli in combination leads to increased re-swelling. The study demonstrates the effect of structural defects on the responsive behavior of thin hydrogel films and simultaneously provides an easy method to fix such defects.
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Publisher
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Wiley
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Wikidata
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Citation
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Journal of Polymer Science 63 (2025) 3631-3639
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DOI
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https://doi.org/10.1002/pol.20250397
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Tags
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