Abstract
During the drying of bimodal colloidal suspensions containing particles of various sizes, smaller particles preferentially migrate to the top surface under particular drying conditions, leading to undesirable drying defects in batteries and in other coating applications. Despite extensive previous studies, the migration mechanism is far from being understood because few in situ observations are available to support the hypotheses. To remedy this, we use real-time photoluminescence (PL) microscopy to investigate the migration of small fluorescent latex particles co-dispersing with large nonemissive latex particles. Comparing the measured PL intensity with that predicted by a model allows us to determine the quantity of small particles near the evaporating surface. The results reveal that the fluorescent particles segregate in two steps: The primary segregation occurs early in the evaporation stage, whereas the secondary stepwise migration occurs when the air–liquid interface invades the particle consolidation layer. The latter migration is attributed to the flow-induced motion of small particles that move through interstitial spaces between large particles.
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References
Cardinal, CM, Jung, YD, Ahn, KH, Francis, LF, “Drying Regime Maps for Particulate Coatings,” AIChE J., 56 2769–2780 (2010)
Routh, AF, Zimmerman, WB, “Distribution of Particles During Solvent Evaporation from Films,” Chem Eng Sci., 59 2961–2968 (2004)
Luo, H, Cardinal, CM, Scriven, LE, Francis, FL, “Ceramic Nanoparticle/Monodisperse Latex Coatings,” Langmuir, 24 5552–5561 (2008)
Nikiforow, I, Adams, J, Koenig, M, Langhoff, A, Pohl, K, Turshatov, A, Johannsmann, D, “Self-stratification During Film Formation from Latex Blends Driven by Differences in Collective Diffusivity,” Langmuir, 26 13162–13167 (2010)
Atmuri, AK, Bhatia, SR, Routh, AF, “Auto-Stratification in Drying Colloidal Dispersions: Effect of Particle Interactions,” Langmuir, 28 2652–2658 (2012)
Lim, S, Ahn, KH, Yamamura, M, “Latex Migration in Battery Slurries During Drying,” Langmuir, 29 8233–8244 (2013)
Trueman, RE, Domingues, EL, Emmett, SN, Murray, MW, Keddie, JL, Routh, AF, “Auto-Stratification in Drying Colloidal Dispersions: Experimental Investigations,” Langmuir, 28 3420–3428 (2012)
Tzitzinou, A, Keddie, JL, “Film Formation of Latex Blends with Bimodal Particle Size Distributions: Consideration of Particle Deformability and Continuity of the Dispersed Phase,” Macromolecules, 33 2695–2708 (2000)
Buss, F, Roberts, CC, Crawford, KS, Peters, K, Francis, LF, “Effect of Soluble Polymer Binder on Particle Distribution in a Drying Particulate Coating,” J. Colloid Interface Sci., 359 112–120 (2011)
Trueman, RE, Domingues, EL, Emmett, SN, Murray, MW, Routh, AF, “Auto-Stratification in Drying Colloidal Dispersions: A Diffusive Model,” J. Colloid Interface Sci., 377, 207–212 (2012)
Hagiwara, H, Suszynski, WJ, Francis, LF, “A Raman Spectroscopic Method to Find Binder Distribution in Electrodes During Drying,” J. Coat. Technol. Res., 11 (1) 11–17 (2014)
Jaiser, S, Muller, M, Baunach, M, Bauer, W, Scharfer, P, Schabel, W, “Investigation of Film Solidification and Binder Migration During Drying of Li-Ion Battery Anodes,” J. Power Sources, 318 210–219 (2016)
Acknowledgment
We acknowledge the financial support of the Japan Society for the Promotion of Science (JSPS) KAKENHI (26420766) Grant-in-Aid for Scientific Research C.
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Tashima, T., Yamamura, M. Two-step migration of particles in evaporating bimodal suspension films at high Peclet numbers. J Coat Technol Res 14, 965–970 (2017). https://doi.org/10.1007/s11998-017-9946-1
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DOI: https://doi.org/10.1007/s11998-017-9946-1