Synthesis of Colloidal Silica Dumbbells

Johnson, Patrick; Kats, Carlos M. van; Blaaderen, Alfons van

doi:10.1021/la0518750

Cited by 120 publications

(117 citation statements)

References 45 publications

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“…However, making scalable quantities of purified divalent and higher valence colloidal atoms remains a challenge, owing to the limitations of fractionation by density gradient centrifugation. This difficulty might be overcome by large-scale separations 44 , or developing methods that produce clusters with controlled morphology so that no separation is needed. Indeed, the swelling and functionalization methods we use to make our colloidal particles could readily be adapted for use with clusters made using other recently-developed techniques 22,25,45 .…”

Section: Discussionmentioning

confidence: 99%

Colloids with valence and specific directional bonding

Wang

Breed

et al. 2012

Nature

968

1,072

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The ability to design and assemble 3-dimensional structures from colloidal particles is limited by the absence of specific directional bonds. As a result, complex or low-coordination structures, common in atomic and molecular systems, are rare in the colloidal domain. Here we demonstrate a general method for creating the colloidal analogues of atoms with valence: colloidal particles with chemically functionalized patches that can form highly directional bonds.These "colloidal atoms" possess all the common symmetries-and some uncommon ones-characteristic of hybridized atomic orbitals, including sp, sp 2 , sp 3 , sp 3 d, sp 3 d 2 , and sp 3 d 3 . Functionalizing the patches with DNA with single-stranded sticky ends makes the interactions between patches on different particles programmable, specific, and reversible, thus facilitating the self-assembly of particles into "colloidal molecules," including "molecules" with triangular, tetrahedral, and other bonding symmetries. Because colloidal dynamics are slow, the kinetics of molecule formation can be followed directly by optical microscopy. These new colloidal atoms should enable the assembly of a rich variety of new micro-structured materials. 2 IntroductionThe past decade has seen an explosion in the kinds of colloidal particles that can be synthesized 1,2 , with many new shapes, such as cubes 3 , clusters of spheres 4-6 and dimpled particles 7,8 reported. Because the self-assembly of these particles is largely controlled by their geometry, only a few relatively simple crystals have been made: face-centered and body-centered cubic crystals and variants 9 . Colloidal alloys increase the diversity of structures [10][11][12] , but many structures remain difficult or impossible to make. For example, the diamond lattice, predicted more than 20 years ago to have a full 3-dimensional photonic band gap 13 , still cannot be made by colloidal self-assembly because it requires 4-fold coordination. Without directional bonds, such low-coordination states are unstable.

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Section: Discussionmentioning

confidence: 99%

Colloids with valence and specific directional bonding

Wang

Breed

et al. 2012

Nature

968

1,072

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“…Rodlike [51] or disklike [52] architectures, dumbbell-shaped particles [53,54], and particles with ellipsoidal shape [55,56] have been synthesized and characterized. The size of these particles ranges between 10 nm and 10 µm.…”

Section: Introductionmentioning

confidence: 99%

Critical Casimir interaction of ellipsoidal colloids with a planar wall

Kondrat

Harnau

Dietrich

2009

The Journal of Chemical Physics

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Based on renormalization group concepts and explicit mean field calculations we study the universal contribution to the effective force and torque acting on an ellipsoidal colloidal particle which is dissolved in a critical fluid and is close to a homogeneous planar substrate. At the same closest distance between the substrate and the surface of the particle, the ellipsoidal particle prefers an orientation parallel to the substrate and the magnitude of the fluctuation induced force is larger than if the orientation of the particle is perpendicular to the substrate. The sign of the critical torque acting on the ellipsoidal particle depends on the type of boundary conditions for the order parameter at the particle and substrate surfaces, and on the pivot with respect to which the particle rotates.

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“…A lot of attention has been focussed on needle-shaped rods, either naturally occurring ones such as viruses like Tobacco Mosaic Virus or fd virus [2,4,5], or laboratory-synthesized ones such as Boehmite rods [6]. In recent years, however, a plethora of non-spherical particles have been synthesized that are not extremely elongated, for example: ellipsoidal colloids with aspect ratio ∼ 3 [7]; colloidal dumbbells [8]; or nano-particles with the shape of a rod, disk, snowman, cube, cap, or raspberry, [9,10,11,12,13,14,15]. These particles are often charged when dissolved in a polar solvent like water, and hence their pair-interactions involve not only the anisotropic steric short-range repulsions but also electrostatic long-range repulsions.…”

Section: Introductionmentioning

confidence: 99%

Effective shape and phase behavior of short charged rods

2009

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We explicitly calculate the orientation-dependent second virial coefficient of short charged rods in an electrolytic solvent, assuming the rod-rod interactions to be a pairwise sum of hard-core and segmental screened-Coulomb repulsions. From the parallel and isotropically averaged second virial coefficient, we calculate the effective length and diameter of the rods, for charges and screening lengths that vary over several orders of magnitude. Using these effective dimensions, we determine the phase diagram, where we distinguish a low-charge and strong-screening regime with a liquid crystalline nematic and smectic phase, and a high-charge and weak-screening regime with a plastic crystal phase in the phase diagram.

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Synthesis of Colloidal Silica Dumbbells

Cited by 120 publications

References 45 publications

Colloids with valence and specific directional bonding

Colloids with valence and specific directional bonding

Critical Casimir interaction of ellipsoidal colloids with a planar wall

Effective shape and phase behavior of short charged rods

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