On the role of softness in ionic microgel interactions
Autor: | Sofi Nöjd, Priti S. Mohanty, Maxime J. Bergman, Peter Schurtenberger, Niels Boon, Joakim Stenhammar, J J Erik Maris, Jasper N. Immink |
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Rok vydání: | 2021 |
Předmět: |
Phase transition
Materials science Ionic bonding 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Light scattering 0104 chemical sciences Chemistry Chemical physics Phase (matter) Volume fraction Particle Soft matter 0210 nano-technology Phase diagram |
Zdroj: | Soft Matter |
ISSN: | 1744-6848 1744-683X |
Popis: | Thermoresponsive microgels are a popular model system to study phase transitions in soft matter, because temperature directly controls their volume fraction. Ionic microgels are additionally pH-responsive and possess a rich phase diagram. Although effective interaction potentials between microgel particles have been proposed, these have never been fully tested, leading to a gap in our understanding of the link between single-particle and collective properties. To help resolve this gap, four sets of ionic microgels with varying crosslinker density were synthesised and characterised using light scattering techniques and confocal microscopy. The resultant structural and dynamical information was used to investigate how particle softness affects the phase behaviour of ionic microgels and to validate the proposed interaction potential. We find that the architecture of the microgel plays a marked role in its phase behaviour. Rather than the ionic charges, it is the dangling ends which drive phase transitions and interactions at low concentration. Comparison to theory underlines the need for a refined theoretical model which takes into consideration these close-contact interactions. Dangling ends of ionic microgels influence their interactions significantly, leading to effective hard sphere behaviour rather than benchmark Hertzian–Yukawa predictions. |
Databáze: | OpenAIRE |
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