Interactions between a responsive microgel monolayer and a rigid colloid: from soft to hard interfaces
Responsive poly- N -isopropylacrylamide-based microgels are commonly used as model colloids with soft repulsive interactions. It has been shown that the microgel-microgel interaction in solution can be easily adjusted by varying the environmental parameters, e.g. , temperature, pH, or salt concentra...
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Published in | Physical chemistry chemical physics : PCCP Vol. 23; no. 31; pp. 16754 - 16766 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Cambridge
Royal Society of Chemistry
12.08.2021
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Subjects | |
Online Access | Get full text |
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Summary: | Responsive poly-
N
-isopropylacrylamide-based microgels are commonly used as model colloids with soft repulsive interactions. It has been shown that the microgel-microgel interaction in solution can be easily adjusted by varying the environmental parameters,
e.g.
, temperature, pH, or salt concentration. Furthermore, microgels readily adsorb to liquid-gas and liquid-liquid interfaces forming responsive foams and emulsions that can be broken on-demand. In this work, we explore the interactions between microgel monolayers at the air-water interface and a hard colloid in the water. Force-distance curves between the monolayer and a silica particle were measured with the Monolayer Particle Interaction Apparatus. The measurements were conducted at different temperatures and lateral compressions,
i.e.
, different surface pressures. The force-distance approach curves display long-range repulsive forces below the volume phase transition temperature of the microgels. Temperature and lateral compression reduce the stiffness of the monolayer. The adhesion increases with temperature and decreases with a lateral compression of the monolayer. When compressed laterally, the interactions between the microgels are hardly affected by temperature, as the directly adsorbed microgel fractions are nearly insensitive to temperature. In contrast, our findings show that the temperature-dependent swelling of the microgel fractions in the aqueous phase strongly influences the interaction with the probe. This is explained by a change in the microgel monolayer from a soft to a hard repulsive interface.
We investigated the interaction between microgel monolayers at the air-water interface and a hard colloid in water. Our results show that microgel monolayers change from soft to hard repulsive interfaces when the VPTT is exceeded. |
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Bibliography: | Electronic supplementary information (ESI) available: Characterization in bulk, force-distance curves, surface charge density of the hydrophilpos probe and the air-water interface, approximated surface charge density of microgel monolayers. See DOI 10.1039/d1cp01703a ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1463-9076 1463-9084 |
DOI: | 10.1039/d1cp01703a |