Preparation and characterization of monodisperse polymer microspheroids

Keville, K. M.; Franses, Elias I.; Caruthers, James M.

doi:10.1016/0021-9797(91)90242-z

Cited by 119 publications

(127 citation statements)

References 27 publications

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“…This is accomplished by synthesizing polystyrene-polyvinylpyrrolidone (PS-PVP) spheres by dispersion polymerization (diameter 2a = 820 ± 6nm) (13,14) and PS ellipsoids by mechanical stretching (aspect ratio 5.6 ± 0.6, 2.48 ± 0.15 µm long, 0.45 ± 0.03 µm wide) (15,16). Additional experimental details are provided in SI Appendix.…”

Section: Resultsmentioning

confidence: 99%

Arresting dissolution by interfacial rheology design

Beltramo

Gupta

Alicke

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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A strategy to halt dissolution of particle-coated air bubbles in water based on interfacial rheology design is presented. Whereas previously a dense monolayer was believed to be required for such an "armored bubble" to resist dissolution, in fact engineering a 2D yield stress interface suffices to achieve such performance at submonolayer particle coverages. We use a suite of interfacial rheology techniques to characterize spherical and ellipsoidal particles at an air-water interface as a function of surface coverage. Bubbles with varying particle coverages are made and their resistance to dissolution evaluated using a microfluidic technique. Whereas a bare bubble only has a single pressure at which a given radius is stable, we find a range of pressures over which bubble dissolution is arrested for armored bubbles. The link between interfacial rheology and macroscopic dissolution of ∼ 100 µm bubbles coated with ∼ 1 µm particles is presented and discussed. The generic design rationale is confirmed by using nonspherical particles, which develop significant yield stress at even lower surface coverages. Hence, it can be applied to successfully inhibit Ostwald ripening in a multitude of foam and emulsion applications.interfacial rheology | foams | yield stress | Ostwald ripening | emulsions T uning the interparticle interaction potential in bulk suspensions has long been a strategy to engineer the properties of colloidal suspensions. In this work, we apply this paradigm to interfacial materials, specifically particle-stabilized drops and bubbles. These systems with high interfacial area have broad applicability from food formulation and processing (1, 2), encapsulation (3, 4), ultrasound medical technologies (5), to lowweight/high-strength materials (6). One of the key challenges in using solid stabilized emulsions and foams in applications is curtailing Ostwald ripening, which causes the growth/shrinkage of large/small bubbles and increased size heterogeneity (7).Ripening occurs due to differences in the Laplace pressure in bubbles of different radii; large bubbles grow, while small bubbles shrink. This suggests that strategies to impart a resistance to dilation or compression of the interface would retard or entirely stop Ostwald ripening. Previously, fully covered, "jammed," particle coated bubbles were shown to fully resist dissolution of this nature (8)(9)(10)(11)(12). When the ratio of particle size to bubble size is large (a/R > 0.1), specific faceted shapes may moreover reduce the mean curvature to zero, thereby reducing the driving force to zero (10). However, stability is also observed at much smaller a/R ratios, suggesting other factors come into play. Previous work supposed the particles do not interact with each other, but since such interactions have a major role in interfacial rheology, they can potentially contribute to bulk bubble and emulsion stability as well.Here, we design and characterize model viscoplastic interfacial systems consisting of spherical and nonspherical particles at an air-water int...

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Section: Resultsmentioning

confidence: 99%

Arresting dissolution by interfacial rheology design

Beltramo

Gupta

Alicke

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Polymer beads can be converted into ellipsoidal particles by viscoelastic deformation at an elevated temperature. [323] Similarly, macroporous polymers (inverse opal) can be compressed or extended to form unusual void shapes. [85] Such oval-shaped polymer beads or voids have been employed as templates for preparation of eggshell-like TiO 2 hollow particles.…”

Section: Hard Templating Synthesis Of Non-spherical Hollow Structuresmentioning

confidence: 99%

Hollow Micro‐/Nanostructures: Synthesis and Applications

2008

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Hollow micro‐/nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best‐known example of the former is the use of fly‐ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro‐/nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well‐established approaches, such as conventional hard‐templating and soft‐templating methods, as well as newly emerging methods based on sacrificial templating and template‐free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle‐type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed.

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“…Several experimental approaches appear promising. Sheu et al [6,7] It is worth mentioning that the model and simulation approach described in this work can be easily extended to study other anisotropic colloidal particles that can be found in recent experiments, such as dumbbell [6,7,30], peanut [30,31], ellipsoid [32], and spindle-like particles [30]. …”

Section: Discussionmentioning

confidence: 99%

Simulation Studies of the Self-Assembly of Cone-Shaped Particles

2007

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We systematically investigate the self-assembly of anisotropic cone-shaped particles decorated by ring-like attractive "patches". We demonstrate that the selfassembled clusters, which arise due to the conical particle's anisotropic shape combined with directional attractive interactions, are precise for certain cluster sizes, resulting in a precise packing sequence of clusters of increasing sizes with decreasing cone angles. We thoroughly explore the dependence of cluster packing on cone angle and cooling rate, and categorize the resulting structures as "stable" and "metastable" clusters. We also discuss the implication of our simulation results in the context of the Israelachvili packing rule for surfactants, and a recent geometrical packing analysis on hard cones in the limit of large numbers of cones.

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Preparation and characterization of monodisperse polymer microspheroids

Cited by 119 publications

References 27 publications

Arresting dissolution by interfacial rheology design

Arresting dissolution by interfacial rheology design

Hollow Micro‐/Nanostructures: Synthesis and Applications

Simulation Studies of the Self-Assembly of Cone-Shaped Particles

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