Authors
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Hofmann, D.; Sychev, D.; Zagradska-Paromova, Z.; Bittrich, E.; Auernhammer, G. K.; Gaitzsch, J.
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Title
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Surface topology of redox- and thermoresponsive nanogel droplets
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Date
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29.04.2024
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Number
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0
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Abstract
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Hydrogels are usually depicted as a homogenous polymer block with a distinct surface. While defects in the polymer structure are looked into frequently, structural irregularities on the hydrogel surface are often neglected. In this work, thin hydrogel layers of ≈100 nm thickness (nanogels) are synthesized and characterized for their structural irregularities, as they represent the surface of macrogels. The nanogels contain a main-chain responsiveness (thermo responsive) and a responsiveness in the cross-linking points (redox responsive). By combining data from ellipsometry using box-model and two-segment-model analysis, as well as atomic force microscopy, a more defined model of the nanogel surface can be developed. Starting with a more densely cross-linked network at the silica wafer surface, the density of cross-linking gradually decreases toward the hydrogel–solvent interface. Thermo-responsive behavior of the main chain affects the entire network equally as all chain segments change solubility. Cross-linker-based redox-responsiveness, on the other hand, is only governed by the inner, more cross-linked layers of the network. Such dual responsive nanogels hence allow for developing a more detailed model of a hydrogel surface from free radical polymerization. It provides a better understanding of structural defects in hydrogels and how they are affected by responsive functionalities.
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Publisher
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Wiley
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Wikidata
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Citation
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Macromolecular Rapid Communications 45 (2024) 2400049
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DOI
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https://doi.org/10.1002/marc.202400049
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Tags
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