Two‐step continuous production of monodisperse colloidal ellipsoids at rates of one gram per day

Ferrar, Joseph A.; Pavlovsky, Leonid; Viges, Eric; Liu, Yanliang; Solomon, Michael J.

doi:10.1002/aic.16009

Cited by 8 publications

(6 citation statements)

References 35 publications

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“…Stretching of the polymer spheres into ellipsoids is done through established methods. ,− In brief, the polymer microspheres are cast into a poly(vinyl alcohol) (PVA) solution that is allowed to dry. The film has a thickness of ∼200 μm and is heated in an oil bath to a temperature of T = 115 °C, which is above the glass transition temperatures, T g , of all polymers present ( T g,PtBA = 45 °C, T g,PS = 107 °C, T g,PVA = 75 °C).…”

Section: Methodsmentioning

confidence: 99%

Nanoscale Porosity in Microellipsoids Cloaks Interparticle Capillary Attraction at Fluid Interfaces

et al. 2023

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Anisotropic particles pinned at fluid interfaces tend toward disordered multiparticle configurations due to large, orientationally dependent, capillary forces, which is a significant barrier to exploiting these particles to create functional self-assembled materials. Therefore, current interfacial assembly methods typically focus on isotropic spheres, which have minimal capillary attraction and no dependence on orientation in the plane of the interface. In order to create longrange ordered structures with complex configurations via interfacially trapped anisotropic particles, control over the interparticle interaction energy via external fields and/or particle engineering is necessary. Here, we synthesize colloidal ellipsoids with nanoscale porosity and show that their interparticle capillary attraction at a water−air interface is reduced by an order of magnitude compared to their smooth counterparts. This is accomplished by comparing the behavior of smooth, rough, and porous ellipsoids at a water−air interface. By monitoring the dynamics of two particles approaching one another, we show that the porous particles exhibit a much shorter-range capillary interaction potential, with scaling intriguingly different than theory describing the behavior of smooth ellipsoids. Further, interferometry measurements of the fluid deformation surrounding a single particle shows that the interface around porous ellipsoids does not possess the characteristic quadrupolar symmetry of smooth ellipsoids, and quantitatively confirms the decrease in capillary interaction energy. By engineering nanostructured surface features in this fashion, the interfacial capillary interactions between particles may be controlled, informing an approach for the self-assembly of complex two-dimensional microstructures composed of anisotropic particles.

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Section: Methodsmentioning

confidence: 99%

Nanoscale Porosity in Microellipsoids Cloaks Interparticle Capillary Attraction at Fluid Interfaces

et al. 2023

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“…Many techniques are also limited in throughput and are resource-and energy-intensive, emphasizing the need to develop more scalable and sustainable soft matter fabrication processes. [13][14][15] Thus, one major challenge in the area is the introduction of a nanofabrication technique that can consistently deliver soft polymeric matter of high surface area and complex nanoscale morphology in a scalable, versatile, and easily tunable way.…”

Section: Introductionmentioning

confidence: 99%

Fluid Flow Templating of Polymeric Soft Matter with Diverse Morphologies

et al. 2023

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It is challenging to find a conventional nanofabrication technique that can consistently produce soft polymeric matter of high surface area and nanoscale morphology in a way that is scalable, versatile, and easily tunable. Here, the capabilities of a universal method for fabricating diverse nano‐ and micro‐scale morphologies based on polymer precipitation templated by the fluid streamlines in multiphasic flow are explored. It is shown that while the procedure is operationally simple, various combinations of its intertwined mechanisms can controllably and reproducibly lead to the formation of an extraordinary wide range of colloidal morphologies. By systematically investigating the process conditions, 12 distinct classes of polymer micro‐ and nano‐structures including particles, rods, ribbons, nanosheets, and soft dendritic colloids (dendricolloids) are identified. The outcomes are interpreted by delineating the physical processes into three stages: hydrodynamic shear, capillary and mechanical breakup, and polymer precipitation rate. The insights into the underlying fundamental mechanisms provide guidance toward developing a versatile and scalable nanofabrication platform. It is verified that the liquid shear‐based technique is versatile and works well with many chemically diverse polymers and biopolymers, showing potential as a universal tool for simple and scalable nanofabrication of many morphologically distinct soft matter classes.

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“…We use an AC electric field to drive particle motion and correlate features of the anisotropic particles with those of their dynamical trajectories. We choose prolate polystyrene (PS) ellipsoids as model particles due to their well-established fabrication process from PS spheres. − We use gold as the metal for the surface patches due to its relatively inert nature and stability in aqueous media. We use physical vapor deposition to form gold patches on ellipsoids previously assembled onto a planar substrate.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Electric Field-Driven Active Propulsion of Patchy Microellipsoids

et al. 2021

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Active colloids are a synthetic analogue of biological microorganisms that consume external energy to swim through viscous fluids. Such motion requires breaking the symmetry of the fluid flow in the vicinity of a particle; however, it is challenging to understand how surface and shape anisotropies of the colloid lead to a particular trajectory. Here, we attempt to deconvolute the effects of particle shape and surface anisotropy on the propulsion of model ellipsoids in alternating current (AC) electric fields. We first introduce a simple process for depositing metal patches of various shapes on the surfaces of ellipsoidal particles. We show that the shape of the metal patch is governed by the assembled structure of the ellipsoids on the substrate used for physical vapor deposition. Under high-frequency AC electric field, ellipsoids dispersed in water show linear, circular, and helical trajectories which depend on the shapes of the surface patches. We demonstrate that features of the helical trajectories such as the pitch and diameter can be tuned by varying the degree of patch asymmetry along the two primary axes of the ellipsoids, namely longitudinal and transverse. Our study reveals the role of patch shape on the trajectory of ellipsoidal particles propelled by induced charge electrophoresis. We develop heuristics based on patch asymmetries that can be used to design patchy particles with specified nonlinear trajectories.

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Two‐step continuous production of monodisperse colloidal ellipsoids at rates of one gram per day

Cited by 8 publications

References 35 publications

Nanoscale Porosity in Microellipsoids Cloaks Interparticle Capillary Attraction at Fluid Interfaces

Nanoscale Porosity in Microellipsoids Cloaks Interparticle Capillary Attraction at Fluid Interfaces

Fluid Flow Templating of Polymeric Soft Matter with Diverse Morphologies

Fabrication and Electric Field-Driven Active Propulsion of Patchy Microellipsoids

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