Soft matter systems often exhibit an intriguing morphology, related to the formation of intermediate range order structures. A rationale proposed for this behavior is the presence of competing short-range attraction and long-range repulsion. On the basis that effective interactions among the centers of mass of soft macromolecules often result in a finite short-range repulsion, we here consider a model fluid in which competing interactions supplement a repulsive core that, at difference from the models investigated up to now, has a bounded nature. We study the structural and phase behavior of this model through a theoretical approach and by computer simulation. We find that the structure factor exhibits a low-k peak, which is particularly relevant at low densities, where our system is formed by polydisperse clusters. A distinctive feature characterizing our model fluid is the presence of a peak situated between the low-k peak and the first diffraction peak. We show that this second pre-peak is associated with the enhancement of the relative population of the second coordination shell with respect to the first one, generated at intermediate densities by the long-range repulsion. As it concerns the phase behavior, the system investigated undergoes, for weak long-range repulsion, a liquid-gas phase transition. Upon increasing the strength of the long-range repulsion, such transition becomes less evident and eventually disappears. At high densities, the system undergoes freezing into a clustered solid, with multiply occupied crystal sites.

Aggregate formation in fluids with bounded repulsive core and competing interactions / Malescio, G.; Sciortino, F.. - In: JOURNAL OF MOLECULAR LIQUIDS. - ISSN 0167-7322. - 303:(2020). [10.1016/j.molliq.2020.112601]

Aggregate formation in fluids with bounded repulsive core and competing interactions

Sciortino F.
2020

Abstract

Soft matter systems often exhibit an intriguing morphology, related to the formation of intermediate range order structures. A rationale proposed for this behavior is the presence of competing short-range attraction and long-range repulsion. On the basis that effective interactions among the centers of mass of soft macromolecules often result in a finite short-range repulsion, we here consider a model fluid in which competing interactions supplement a repulsive core that, at difference from the models investigated up to now, has a bounded nature. We study the structural and phase behavior of this model through a theoretical approach and by computer simulation. We find that the structure factor exhibits a low-k peak, which is particularly relevant at low densities, where our system is formed by polydisperse clusters. A distinctive feature characterizing our model fluid is the presence of a peak situated between the low-k peak and the first diffraction peak. We show that this second pre-peak is associated with the enhancement of the relative population of the second coordination shell with respect to the first one, generated at intermediate densities by the long-range repulsion. As it concerns the phase behavior, the system investigated undergoes, for weak long-range repulsion, a liquid-gas phase transition. Upon increasing the strength of the long-range repulsion, such transition becomes less evident and eventually disappears. At high densities, the system undergoes freezing into a clustered solid, with multiply occupied crystal sites.
Cluster formation; Fluids with bounded repulsive core; Fluids with microscopic competing interactions; Non-homogeneous liquid phases; Self-assembly in complex liquids; Soft matter
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Aggregate formation in fluids with bounded repulsive core and competing interactions / Malescio, G.; Sciortino, F.. - In: JOURNAL OF MOLECULAR LIQUIDS. - ISSN 0167-7322. - 303:(2020). [10.1016/j.molliq.2020.112601]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1556100
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