Stimuli-responsive behavior of PNiPAm microgels under interfacial confinement

Johannes Harrer, Marcel Rey, Simone Ciarella, Hartmut Löwen, Liesbeth M.C. Janssen, Nicolas Vogel (Corresponding author)

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

Uittreksel

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.

TaalEngels
Pagina's10512-10521
Aantal pagina's10
TijdschriftLangmuir
Volume35
Nummer van het tijdschrift32
DOI's
StatusGepubliceerd - 14 jul 2019

Vingerafdruk

stimuli
Phase transitions
Polymers
liquid air
molecular properties
destabilization
polymers
Emulsions
confining
Free energy
emulsions
Surface tension
Hysteresis
Molecular dynamics
interfacial tension
free energy
hysteresis
molecular dynamics
Cooling
cooling

Citeer dit

Harrer, Johannes ; Rey, Marcel ; Ciarella, Simone ; Löwen, Hartmut ; Janssen, Liesbeth M.C. ; Vogel, Nicolas. / Stimuli-responsive behavior of PNiPAm microgels under interfacial confinement. In: Langmuir. 2019 ; Vol. 35, Nr. 32. blz. 10512-10521
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Stimuli-responsive behavior of PNiPAm microgels under interfacial confinement. / Harrer, Johannes; Rey, Marcel; Ciarella, Simone; Löwen, Hartmut; Janssen, Liesbeth M.C.; Vogel, Nicolas (Corresponding author).

In: Langmuir, Vol. 35, Nr. 32, 14.07.2019, blz. 10512-10521.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

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Harrer J, Rey M, Ciarella S, Löwen H, Janssen LMC, Vogel N. Stimuli-responsive behavior of PNiPAm microgels under interfacial confinement. Langmuir. 2019 jul 14;35(32):10512-10521. Beschikbaar vanaf, DOI: 10.1021/acs.langmuir.9b01208