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Nanoparticle separation based on size-dependent aggregation of nanoparticles due to the critical Casimir effect

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Abstract

Nanoparticles typically have an inherent wide size distribution that may affect the performance and reliability of many nanomaterials. Because the synthesis and purification of nanoparticles with desirable sizes are crucial to the applications of nanoparticles in various fields including medicine, biology, health care, and energy, there is a great need to search for more efficient and generic methods for size-selective nanoparticle purification/separation. Here we propose and conclusively demonstrate the effectiveness of a size-selective particle purification/separation method based on the critical Casimir force. The critical Casimir force is a generic interaction between colloidal particles near the solvent critical point and has been extensively studied in the past several decades due to its importance in reversibly controlling the aggregation and stability of colloidal particles. Combining multiple experimental techniques, we found that the critical Casimir force-induced aggregation depends on relative particle sizes in a system with larger ones aggregating first and the smaller ones remaining in solution. Based on this observation, a new size-dependent nanoparticle purification/separation method is proposed and demonstrated to be very efficient in purifying commercial silica nanoparticles in the lutidine/water binary solvent. Due to the ubiquity of the critical Casimir force for many colloidal particles in binary solvents, this method might be applicable to many types of colloidal particles.

Graphical abstract: Nanoparticle separation based on size-dependent aggregation of nanoparticles due to the critical Casimir effect

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Publication details

The article was received on 02 Oct 2017, accepted on 24 Dec 2017 and first published on 02 Jan 2018


Article type: Paper
DOI: 10.1039/C7SM01971H
Citation: Soft Matter, 2018, Advance Article
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    Nanoparticle separation based on size-dependent aggregation of nanoparticles due to the critical Casimir effect

    H. Guo, G. Stan and Y. Liu, Soft Matter, 2018, Advance Article , DOI: 10.1039/C7SM01971H

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