Modified Spin-coating Technique to Achieve Directional Colloidal Crystallization

Bartlett, Andrew; Pichumani, Moorthi; Giuliani, Maximiliano; González-Viñas, Wenceslao; Yethiraj, Anand

doi:10.1021/la204123s

Cited by 28 publications

(30 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Spin-coating of nano-colloids has been thoroughly explored in the literature for almost a century [1]. However, for colloids of bigger particles, external fields have been used recently for tunning their effect which is not yet fully understood [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Spin-coating of moderately concentrated superparamagnetic colloids in different magnetic field configurations

Aslam

González-Viñas

2017

Colloids and Surfaces A: Physicochemical and Engineering Aspect

View full text Add to dashboard Cite

Spin-coating technique is very fast, cheap, reproducible, simple and needs less material to fabricate films of particulate systems/colloids. Their thickness and uniformity may be controlled by means of external fields. We apply magnetic fields during the spin-coating of a moderately concentrated superparamagnetic colloid (made of silica coated magnetite particles). We study the influence of different magnetic field configurations (homogeneous and inhomogeneous) on the resulting spincoated deposits and compare experimental results under various conditions. Superparamagnetic colloids behave as, non-Newtonian, magnetorheological fluids. Their viscosity vary significantly under applied magnetic fields. We measure and compare the effect of uniform and non-uniform magnetic fields on their relative effective viscosity, using the spin-coated deposits and a previously existing model for simple colloids. The mechanisms involved in the deposits formation under different experimental conditions are also discussed. In particular, we show that the magnetophoretic effect plays an important role in the spin-coating of magnetic colloids subjected to non-uniform magnetic fields. We characterize an effective magnetoviscosity in non-uniform magnetic fields that is largely influenced by the magnetophoretic effect that enhances the flow of the magnetic fluid.

show abstract

Section: Introductionmentioning

confidence: 99%

Spin-coating of moderately concentrated superparamagnetic colloids in different magnetic field configurations

Aslam

González-Viñas

2017

Colloids and Surfaces A: Physicochemical and Engineering Aspect

View full text Add to dashboard Cite

show abstract

“…Recently, it was demonstrated that the application of a nonuniform electric field while spin coating affects the hydrodynamic flows through dispersion-air dielectric contrast 20 . By arranging the alternating field direction to be fixed in the rotating frame, the axial symmetry from spinning is broken.…”

Section: Nature Of the Orientational Order And The Colored Patternsmentioning

confidence: 99%

“…The application of an electric field also changes the net domain orientation, as shown in Fig. 8, because hydrodynamic shear forces and the electrostatic forces compete to orient the domains 20 . These changes in orientation have been assessed with quantitative image processing algorithms 43 .…”

Section: Nature Of the Orientational Order And The Colored Patternsmentioning

confidence: 99%

Dynamics, crystallization and structures in colloid spin coating

et al. 2013

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…Electric fields have been applied during spin-coating of colloids to produce translationally ordered structures in Refs. [25,26]. Thus, if one can overcome the primary challenge set by the axial symmetry of spin coating, i.e., the emergence of OCPs, numerous ways to achieve better order would arise.…”

Section: Introductionmentioning

confidence: 99%

Quantifying disorder in colloidal films spin-coated onto patterned substrates

et al. 2017

Self Cite

View full text Add to dashboard Cite

Polycrystals of thin colloidal deposits, with thickness controlled by spin-coating speed, exhibit axial symmetry with local 4-fold and 6-fold symmetric structures, termed orientationally correlated polycrystals (OCPs). While spin-coating is a very facile technique for producing large-area colloidal deposits, the axial symmetry prevents us from achieving true long-range order. To obtain true long-range order, we break this axial symmetry by introducing a patterned surface topography and thus eliminate the OCP character. We then examine symmetryindependent methods to quantify order in these disordered colloidal deposits. We find that all the information in the bond-orientational order parameters is well captured by persistent homology analysis methods that only use the centers of the particles as input data. It is expected that these methods will prove useful in characterizing other disordered structures.

show abstract

Modified Spin-coating Technique to Achieve Directional Colloidal Crystallization

Cited by 28 publications

References 37 publications

Spin-coating of moderately concentrated superparamagnetic colloids in different magnetic field configurations

Spin-coating of moderately concentrated superparamagnetic colloids in different magnetic field configurations

Dynamics, crystallization and structures in colloid spin coating

Quantifying disorder in colloidal films spin-coated onto patterned substrates

Contact Info

Product

Resources

About