Drying paint: from micro-scale dynamics to mechanical instabilities

Abstract

Charged colloidal dispersions make up the basis of a broad range of industrial and commercial products, from paints to coatings and additives in cosmetics. During drying, an initially liquid dispersion of such particles is slowly concentrated into a solid, displaying a range of mechanical instabilities in response to highly variable internal pressures. Here we summarise the current appreciation of this process by pairing an advection-diffusion model of particle motion with a Poisson-Boltzmann cell model of inter-particle interactions, to predict the concentration gradients around a drying colloidal film. We then test these predictions with osmotic compression experiments on colloidal silica, and small-angle x-ray scattering experiments on silica dispersions drying in Hele-Shaw cells. Finally, we use the details of the microscopic physics at play in these dispersions to explore how two macroscopic mechanical instabilities -- shear-banding and fracture -- can be controlled.

20 pages, 11 figures

References in corpus (6)

• Hiding in plain view: Colloidal self-assembly from polydisperse populations
• Structural anisotropy of directionally dried colloids
• Drying and deposition of poly(ethylene oxide) droplets determined by Péclet number
• Crack patterns over uneven substrates
• Formation of shear-bands in drying colloidal dispersions
• The polydisperse cell model: Non-linear screening and charge renormalization in colloidal mixtures

Cited by in corpus (9)

• Universal Scaling of Polygonal Desiccation Crack Patterns
• Collective diffusion coefficient of a charged colloidal dispersion: interferometric measurements in a drying drop
• Microfluidic free interface diffusion: measurement of diffusion coefficients and evidence of interfacial-driven transport phenomena
• Packing polydisperse colloids into crystals: when charge-dispersity matters
• Dynamics and ordering of weakly Brownian particles in directional drying
• Microfluidic osmotic compression of a charge-stabilized colloidal dispersion: Equation of state and collective diffusion coefficient
• Jellium and Cell Model for Titratable Colloids with Continuous Size Distribution
• Confined drying of a binary liquid mixture droplet: A quantitative interferometric study under humidity control
• Experimental investigations on the nonequilibrium dynamics of pattern formation in fluid and granular systems