Spin coating of colloidal suspensions

Rehg, Timothy J.; Higgins, Gwendolyn

doi:10.1002/aic.690380403

Cited by 71 publications

(53 citation statements)

References 36 publications

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“…12 A recent work demonstrates that spin-coating flows (in the absence of evaporation) control the local stress profiles, and drive crystallization when the Peclet number exceeds a critical value. 6 Two questions that have remained unaddressed;how the dynamics interlinks with the emergence of different symmetries, and the role played by evaporation;are the focus of the experiments reported here.…”

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confidence: 99%

“…In 2010, 1, 1481-1486 pubs.acs.org/JPCL addition, this universal behavior looks similar to (and can in principle be compared with) the numerical thinning rates calculated by Rehg and Higgins. 12 Having considered the dynamics in the fluid phase, we next consider the movement of the drying front (Figure 3a). In all cases studied, the speed at which the interface moves toward the center presents two distinct dynamical regimes (Figure 3b): an early stage where front speeds are large and increase in magnitude with increasing rotation speed, and a late stage where front speeds are small and invariant with rotation speed.…”

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confidence: 99%

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Dynamics of Crystal Structure Formation in Spin-Coated Colloidal Films

Giuliani

González-Viñas

Poduska

et al. 2010

J. Phys. Chem. Lett.

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The spin-coating of colloidal suspensions is an inherently nonequilibrium process that gives rise to highly reproducible, but polycrystalline, films with different symmetries depending on experimental parameters. In this study, we explore the transient dynamics of evaporative colloid spin-coating for the first time, via a combination of high-speed imaging, atomic force microscopy, static photography, and scanning electron microscopy. As the wet colloidal film thins and dries, we observe several symmetry transitions, while at the same time remarkably, the thinning rate (in nondimensional time units) collapses to one universal curve for all rotation rates. We correlate static and dynamic measures of crossovers in ordering regimes, and obtain an estimate of the evaporation rate in the late stage of drying. We conclude that the thinning dynamics controls the local volume fraction and stress profiles, which in turn drives the structural transitions. SECTION Macromolecules, Soft Matter C olloidal self-assembly is a facile and promising method for making photonic crystals, 1 but the control of defects is a challenge. Nonequilibrium approaches to colloidal self-assembly are likely crucial to the making of large-area colloidal crystals.2,3 Colloid spin-coating has recently emerged as a highly robust and reproducible nonequilibrium method to make multilayer colloidal crystalline films. [4][5][6] However, in spite of its robustness, the spin-coating route to colloidal crystals is fraught with challenges. The highly uniform structural colors exhibited by these films have been shown to arise from a polycrystal where different crystallites exhibit longrange orientational order. 7 In order to develop strategies to produce crystals with a greater degree of translational order, a deeper understanding of the dynamical mechanisms of structure formation is required.While the dynamics of spin-coating has been studied extensively and quantitatively in simple one-component fluids 8,9 as well as in polymer solutions, 10,11 the study of the dynamics of colloid spin-coating has been limited to numerical studies of thinning rates.12 A recent work demonstrates that spin-coating flows (in the absence of evaporation) control the local stress profiles, and drive crystallization when the Peclet number exceeds a critical value. 6 Two questions that have remained unaddressed;how the dynamics interlinks with the emergence of different symmetries, and the role played by evaporation;are the focus of the experiments reported here.We begin with our observations of the transient dynamics. Using high-speed imaging and the lighting configuration A (Figure 6), we are sensitive to changes in long-range orientational order via the appearance of symmetries in the optical reflections. In all experiments (at varying rotation speeds) common dynamical features are observed in the fluid phase. While the results presented here pertain to experiments using methyl ethyl ketone (MEK) as solvent, similar results were found with acetone as solvent. This phase...

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confidence: 99%

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confidence: 99%

Dynamics of Crystal Structure Formation in Spin-Coated Colloidal Films

Giuliani

González-Viñas

Poduska

et al. 2010

J. Phys. Chem. Lett.

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“…Later, Cregan et al 32 generalized this result by considering solvent evaporation in both stages. Rotation-rate dependent diffusion and advection of the solvent, in both vapor and liquid phases, could affect evaporation rate 19,22,29,31,32 , thereby yielding different thicknesses for the deposited layers. Due to drainage and evaporation of the solvent, film thickness (and its rate of thinning) changes continuously as a function of time.…”

Section: Dynamicsmentioning

confidence: 99%

Dynamics, crystallization and structures in colloid spin coating

et al. 2013

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Spin coating is an out-of-equilibrium technique for producing polymer films and colloidal crystals quickly and reproducibly. In this review, we present an overview of theoretical and experimental studies of the spin coating of colloidal suspensions. The dynamics of the spin coating process is discussed first, and we present insights from both theory and experiment. A key difference between spin coating with polymer solutions and with monodisperse colloidal suspensions is the emergence of long range (centimeter scale) orientational correlations in the latter. We discuss experiments in different physical regimes that shed light on the many unusual partially-ordered structures that have long-range orientational order, but no long-range translational order. The nature of these structures can be tailored by adding electric or magnetic fields during the spin coating procedure. These partially-ordered structures can be considered as model systems for studying the fundamentals of poorly crystalline and defect-rich solids, and they can also serve as templates for patterned and/or porous optical and magnetic materials.

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“…However, the spin coating is a process far more complicated than it appears and the underlying mechanism remains in debate. Rehg and Higgins have conducted a theoretical analysis of the physics governing spin coating of a colloidal particle suspension on a planar substrate [24]. Jiang and Mcfarland have succeeded in fabrication of wafer scale long-rang ordered and nonclose-packed 2D and 3D colloidal crystals by spin coating of highly viscous triacrylate suspension of silica particles and subsequent polymerization of triacrylate, followed by partial removal of the polymer matrices [25,26].…”

Section: Spin Coatingmentioning

confidence: 99%