title: Particle Segregation at Contact Lines of Evaporating Colloidal Drops: Influence of the Substrate Wettability and Particle Charge-Mass Ratio.
abstract: Segregation of particles during capillary/convective self-assembly is interesting for self-stratification in colloidal deposits. In evaporating drops containing colloidal particles, the wettability properties of substrate and the sedimentation of particles can affect their accumulation at contact lines. In this work we studied the size segregation and discrimination of charged particles with different densities. We performed in-plane particle counting at evaporating triple lines by using fluorescence confocal microscopy. We studied separately substrates with very different wettability properties and particles with different charge-mass ratios at low ionic strength. We used binary colloidal suspensions to compare simultaneously the deposition of two different particles. The particle deposition rate strongly depends on the receding contact angle of the substrate. We further observed a singular behavior of charged polystyrene particles in binary mixtures under "salt-free" conditions explained by the "colloidal Brazil nut" effect.
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Noguera-Marín
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Moraila-Martínez
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Cabrerizo-Vílchez
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Rodríguez-Valverde
mesh_terms: D003102:Colloids / Q000737:chemistry; D010316:Particle Size; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013499:Surface Properties; D017155:Wettability
chemical_list: D003102:Colloids; D019904:Polymethyl Methacrylate