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Concentration and Size Effects on the Size-Selective Particle Purification Method using the Critical Casimir Force



Jose Ramon Villanueva-Valencia, Hongyu Guo, Ramon Castaneda-Priego, Yun Liu


Critical Casimir force (CCF) is a solvent fluctuation introduced interaction between particles dispersed in a binary sol-vent. Recently, it has been demonstrated that the CCF induced attraction between particles can cause the particle size-sensitive aggregation, and is thus used as an efficient way to purify nanoparticles by sizes. Here, combining small angle neutron scattering and dynamic light scattering, we investigate the effects of size and concentration on this particle size separation method. Increasing the concentration to higher value does not significantly affect the purification method, but the solvent composition needs to be adjusted for an optimized efficiency. This purification method is further demonstrat-ed to work also very efficiently for systems with the particle size ranges from 15 nm to about 50 nm with a very large polydispersity. Thus, these results indicate that for both short-ranged and long- ranged attraction relative to the particle diameters, the CCF introduced particle aggregation is always size sensitive. Thus, this implies that the particle aggregation is strongly affected by its size polydispersity for many colloidal systems. We further propose a method to use the light scattering to help identify the temperature range within which this particle purification method can work efficiently in-stead of using neutron scattering.
Physical Chemistry Chemical Physics


small angle neutron scattering, critical Casimir force, particle purification


Villanueva-Valencia, J. , Guo, H. , Castaneda-Priego, R. and Liu, Y. (2021), Concentration and Size Effects on the Size-Selective Particle Purification Method using the Critical Casimir Force, Physical Chemistry Chemical Physics (Accessed June 16, 2024)


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Created February 25, 2021, Updated April 13, 2022