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Stratification in Drying Films Containing Bidisperse Mixtures of Nanoparticles

Journal Article · · Langmuir
 [1];  [2];  [1]
  1. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Large scale molecular dynamics simulations for bidisperse nanoparticle suspensions with an explicit solvent are used to investigate the effects of evaporation rates and volume fractions on the nanoparticle distribution during drying. Our results show that “small-on-top” stratification can occur when PesΦs ≳ c with c ~1, where Pes is the Péclet number and Φs is the volume fraction of the smaller particles. This threshold of PesΦs for “small-on-top” is larger by a factor of ~α2 than the prediction of the model treating solvent as an implicit viscous background, where α is the size ratio between the large and small particles. Our simulations further show that when the evaporation rate of the solvent is reduced, the “small-on-top” stratification can be enhanced, which is not predicted by existing theories. This unexpected behavior is explained with thermophoresis associated with a positive gradient of solvent density caused by evaporative cooling at the liquid/vapor interface. For ultrafast evaporation the gradient is large and drives the nanoparticles toward the liquid/vapor interface. This phoretic effect is stronger for larger nanoparticles, and consequently the “small-on-top” stratification becomes more distinct when the evaporation rate is slower (but not too slow such that a uniform distribution of nanoparticles in the drying film is produced), as thermophoresis that favors larger particles on the top is mitigated. A similar effect can lead to “large-on-top” stratification for PesΦs above the threshold when Pes is large but Φs is small. Lastly, our results reveal the importance of including the solvent explicitly when modeling evaporation-induced particle separation and organization and point to the important role of density gradients brought about by ultrafast evaporation.

Research Organization:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC04-94AL85000
OSTI ID:
1457520
Report Number(s):
SAND--2018-6692J; 664619
Journal Information:
Langmuir, Journal Name: Langmuir Journal Issue: 24 Vol. 34; ISSN 0743-7463
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

References (41)

Fast Parallel Algorithms for Short-Range Molecular Dynamics journal March 1995
Distribution of particles during solvent evaporation from films journal July 2004
Accurate and efficient methods for modeling colloidal mixtures in an explicit solvent using molecular dynamics journal September 2008
Auto-stratification in drying colloidal dispersions: A diffusive model journal July 2012
Stratification during evaporative assembly of multicomponent nanoparticle films journal April 2018
Expressions for the Evaporation and Condensation Coefficients in the Hertz-Knudsen Relation journal June 2016
Stratification Dynamics in Drying Colloidal Mixtures journal April 2017
Stratification and Size Segregation of Ternary and Polydisperse Colloidal Suspensions during Drying journal May 2017
Assembly of Branched Colloidal Nanocrystals in Polymer Films Leads to Enhanced Viscous Deformation Resistance journal September 2016
pH-Switchable Stratification of Colloidal Coatings: Surfaces “On Demand” journal December 2016
Dispersing Nanoparticles in a Polymer Film via Solvent Evaporation journal May 2016
Fast Assembly of Gold Nanoparticles in Large-Area 2D Nanogrids Using a One-Step, Near-Infrared Radiation-Assisted Evaporation Process journal January 2016
Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology journal February 2017
Self-Stratification During Film Formation from Latex Blends Driven by Differences in Collective Diffusivity journal August 2010
Autostratification in Drying Colloidal Dispersions: Experimental Investigations journal February 2012
Autostratification in Drying Colloidal Dispersions: Effect of Particle Interactions journal January 2012
Ceramic Nanoparticle/Monodisperse Latex Coatings journal April 2008
The Critical Role of Solvent Evaporation on the Roughness of Spin-Cast Polymer Films journal July 2001
Role of Casting Solvent on Nanoparticle Dispersion in Polymer Nanocomposites journal July 2014
Instabilities in Nanoporous Media journal January 2007
Fabrication of Arrays of Metal and Metal Oxide Nanotubes by Shadow Evaporation journal March 2008
Evaporation-Induced Assembly of Quantum Dots into Nanorings journal December 2008
Kinetically driven self assembly of highly ordered nanoparticle monolayers journal March 2006
Machine learning for autonomous crystal structure identification journal January 2017
Stratification in binary colloidal polymer films: experiment and simulations journal January 2017
On Interaction between Two Bodies Immersed in a Solution of Macromolecules journal July 1954
Effective potentials between nanoparticles in suspension journal April 2011
Evaporation of Lennard-Jones fluids journal June 2011
Structure and diffusion of nanoparticle monolayers floating at liquid/vapor interfaces: A molecular dynamics study journal June 2012
Molecular dynamics simulations of evaporation-induced nanoparticle assembly journal February 2013
Communication: Evaporation: Influence of heat transport in the liquid on the interface temperature and the particle flux journal August 2016
Ordering nanoparticles with polymer brushes journal December 2017
Stratification of mixtures in evaporating liquid films occurs only for a range of volume fractions of the smaller component journal April 2018
Drying of thin colloidal films journal March 2013
Interaction potentials for soft and hard ellipsoids journal April 2003
Shear thinning of nanoparticle suspensions journal February 2009
Phoresis in fluids journal December 2011
Diffusiophoresis in nonadsorbing polymer solutions: The Asakura-Oosawa model and stratification in drying films journal December 2017
Dynamic Stratification in Drying Films of Colloidal Mixtures journal March 2016
Cross Interaction Drives Stratification in Drying Film of Binary Colloidal Mixtures journal March 2017
Simple Model of Skin Formation Caused by Solvent Evaporation in Polymer Solutions journal September 2006

Cited By (10)

Segregation in Drying Binary Colloidal Droplets journal March 2019
Experimental and theoretical evidence for molecular forces driving surface segregation in photonic colloidal assemblies journal September 2019
A critical and quantitative review of the stratification of particles during the drying of colloidal films journal January 2018
Directional freezing of binary colloidal suspensions: a model for size fractionation of graphene oxide journal January 2019
Stratification in the dynamics of sedimenting colloidal platelet–sphere mixtures journal January 2019
Influence of hydrodynamic interactions on stratification in drying mixtures journal July 2018
Evaporation-induced assembly of colloidal crystals journal September 2018
Stratification of drying particle suspensions: Comparison of implicit and explicit solvent simulations journal June 2019
Evaporation sampled by stationary molecular dynamics simulation journal July 2019
Stratification of drying particle suspensions: Comparison of implicit and explicit solvent simulations text January 2018

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