Stimuli-Responsive Behavior of PNiPAm Microgels under Interfacial Confinement

Harrer J, Rey M, Ciarella S, Löwen H, Janssen LM, Vogel N (2019)

Publication Type: Journal article

Publication year: 2019

Journal

Langmuir American Chemical Society

DOI: 10.1021/acs.langmuir.9b01208

Abstract

The volume phase transition of microgels is one of the most paradigmatic examples of stimuli-responsiveness, enabling a collapse from a highly swollen microgel state into a densely coiled state by an external stimulus. Although well characterized in bulk, it remains unclear how the phase transition is affected by the presence of a confining interface. Here, we demonstrate that the temperature-induced volume phase transition of poly(N-isopropylacrylamide) microgels, conventionally considered an intrinsic molecular property of the polymer, is in fact largely suppressed when the microgel is adsorbed to an air/liquid interface. We further observe a hysteresis in the core morphology and interfacial pressure between heating and cooling cycles. Our results, supported by molecular dynamics simulations, reveal that the dangling polymer chains of microgel particles, spread at the interface under the influence of surface tension, do not undergo any volume phase transition. The balance in free energy responsible for the volume phase transition is fundamentally altered by interfacial confinement. These results imply that important technological properties of such systems, including the temperature-induced destabilization of emulsions, do not occur via a decrease in the interfacial coverage of the microgels.

Authors with CRIS profile

Johannes Menath Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik Marcel Rey Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik Nicolas Vogel Professur für Partikelsynthese

Involved external institutions

Eindhoven University of Technology / Technische Universiteit Eindhoven (TU/e) NL Netherlands (NL) Heinrich-Heine-Universität Düsseldorf DE Germany (DE)

How to cite

APA:

Harrer, J., Rey, M., Ciarella, S., Löwen, H., Janssen, L.M., & Vogel, N. (2019). Stimuli-Responsive Behavior of PNiPAm Microgels under Interfacial Confinement. Langmuir. https://dx.doi.org/10.1021/acs.langmuir.9b01208

MLA:

Harrer, Johannes, et al. "Stimuli-Responsive Behavior of PNiPAm Microgels under Interfacial Confinement." Langmuir (2019).

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