Inner Structure of Adsorbed Ionic Microgel Particles

Wellert, Stefan; Hertle, Yvonne; Richter, M.; Medebach, Martin; Magerl, David; Wang, Weinan; Demé, Bruno; Rădulescu, Aurel; Müller‐Buschbaum, Peter; Hellweg, Thomas; Klitzing, Regine von

doi:10.1021/la500390j

Cited by 44 publications

(40 citation statements)

References 62 publications

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“…These findings provide robust evidence of the reduced flexibility of the microgels at a liquid-liquid interface, an issue that up to now has either been extracted from indirect results or sometimes related to charge effects [68,69]. Instead, we directly prove that it is entirely attributable to the presence of the interface, where microgels assume a much more stretched configuration with respect to their standard arrangement in bulk.…”

Section: B Elasticity Theory Calculationssupporting

confidence: 56%

Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics

et al. 2020

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Soft colloids are increasingly used as model systems to address fundamental issues such as crystallization and the glass and jamming transitions. Among the available classes of soft colloids, microgels are emerging as the gold standard. Since their great internal complexity makes their theoretical characterization very hard, microgels are commonly modeled, at least in the small-deformation regime, within the simple framework of linear elasticity theory. Here we show that there exist conditions where its range of validity can be greatly extended, providing strong numerical evidence that microgels adsorbed at an interface follow the two-dimensional Hertzian theory, and hence behave like 2D elastic particles, up to very large deformations, in stark contrast to what found in bulk conditions. We are also able to estimate Young's modulus of the individual particles and, by comparing it with its counterpart in bulk conditions, we demonstrate a significant stiffening of the polymer network at the interface. Finally, by analyzing dynamical properties, we predict multiple reentrant phenomena: By a continuous increase of particle density, microgels first arrest and then refluidify due to the high penetrability of their extended coronas. We observe this anomalous behavior in a range of experimentally accessible conditions for small and loosely cross-linked microgels. The present work thus establishes microgels at interfaces as a new model system for fundamental investigations, paving the way for the experimental synthesis and research on unique highdensity liquidlike states. In addition, these results can guide the development of novel assembly and patterning strategies on surfaces and the design of novel materials with desired interfacial behavior.

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Section: B Elasticity Theory Calculationssupporting

confidence: 56%

Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics

et al. 2020

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“…This surprising observation is in contrast to many SANS experiments on microgel dispersions and illustrates the effect of the solid substrate on the polymer network ∘ C properties. Nevertheless, the particle films still shrink and swell reversibly in the adsorbed state [105].…”

Section: Swelling/deswelling At Interfacesmentioning

confidence: 99%

Responsive Microgels at Surfaces and Interfaces

Wellert

Richter

Hellweg

et al. 2014

Zeitschrift Für Physikalische Chemie

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Stimuli responsive surface structures attract increasing attention due to a large variety of envisioned applications. The controlled organization of poly(N-isopropyl acrylamid), PNIPAM microgel particles at solid surfaces inspired numerous research activities. In this review article, we briefly discuss the swelling/deswelling properties of adsorbed microgel particles in comparison to the behavior in the bulk phase. The presence of the solid interface highly influences and changes their behavior with respect to the properties in solution. Furthermore, the confinement on a solid substrate allows the direct and in-situ investigation of the mechanical properties of the microgel particles. Additionally, we briefly review the research on microgel particles at liquid interfaces. At these interfaces new interesting effects occur. Moreover, we discuss some interesting work on potential applications. In this context, microgel particles are often used as an active component for responsive coatings of various functionality envisioning applications, e.g. in medicine, biotechnology, and nanooptics.Zusammenfassung: Responsive Oberflächenmaterialien finden aufgrund der damit verbundenen potentiellen technischen Anwendungsmöglichkeiten große Beachtung in der aktuellen Forschung. Die Möglichkeit, kolloidale Gelpartikel aus poly(N-Isopropylacrylamid), PNIPAM an festen Oberflächen kontrolliert anzuordnen, inspirierte vielfältige Forschungsakivitäten. In diesem Übersichtsartikel diskutieren wir das Quellverhalten adsorbierter Mikrogelpartikel im Vergleich zu

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“…After adsorption onto a solid wafer, the microgels show only one transition between 32 and 45 °C which indicates an interdigitation of the different microphase domains due to compression [16]. Another consequence of the compression is the slowing down of the dynamics within the microgels [22,23].…”

Section: Introductionmentioning

confidence: 99%

Nanomechanics and Nanorheology of Microgels at Interfaces

Backes

Klitzing

2018

Polymers

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The review addresses nanomechanics and nanorheology of stimuli responsive microgels adsorbed at an interface. In order to measure the mechanical properties on a local scale, an atomic force microscope is used. The tip presents an indenter with a radius of curvature of a few 10 s of nm. Static indentation experiments and dynamic studies with an excited cantilever are presented. The effect of several internal and external parameters on the mechanical properties is reviewed. The focus is on the correlation between the swelling abilities of the gels and their mechanical properties. Several results are surprising and show that the relationship is not as simple as one might expect.

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Inner Structure of Adsorbed Ionic Microgel Particles

Cited by 44 publications

References 62 publications

Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics

Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics

Responsive Microgels at Surfaces and Interfaces

Nanomechanics and Nanorheology of Microgels at Interfaces

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