Colloidal Silica Rods: Material Properties and Fluorescent Labeling

Kuijk, Anke; Imhof, Arnout; Verkuijlen, M.H.W.; Besseling, Thijs H.; Eck, Ernst R. H. van; Blaaderen, Alfons van

doi:10.1002/ppsc.201300329

Cited by 48 publications

(88 citation statements)

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“…In a 3D bulk phase at the same packing fraction of ϕ ¼ 0.0026 the rods were found to form a body centered cubic (bcc) plastic crystal and to rotate freely in all directions [22]. Confined between two parallel plates, however, their rotational freedom in the z direction (perpendicular to the walls) was now found to be completely or partially restricted as a function of the wall separation.The charged rods we employed were made of fluorescently labeled silica [24,25] and had a length of 2.29 μm and a diameter of 0.60 μm (see Supplemental Material [26]). They were made hydrophobic by grafting with alkyl chains (C 18 ) and dispersed in the almost index-matching solvent cyclohexyl chloride.…”

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confidence: 99%

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Confinement Induced Plastic Crystal-to-Crystal Transitions in Rodlike Particles with Long-Ranged Repulsion

et al. 2015

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Colloidal particles in geometrical confinement display a complex variety of packing structures different from their three-dimensional (3D) bulk counterpart. Here, we confined charged rodlike colloids with longranged repulsions to a thin wedge-shaped cell and show, by quantitative 3D confocal microscopy, that not only their positional but also their orientational order depends sensitively upon the slit width. Synchronized with transitions in lattice symmetry and number of layers confinement induces plastic crystal-to-crystal transitions. A model analysis suggests that this complex sequence of more or less rotationally ordered states originates from the subtle competition between the electrostatic repulsion of a rod with the wall and with its neighbors. DOI: 10.1103/PhysRevLett.115.078301 PACS numbers: 82.70.Dd, 64.75.Yz When a colloidal suspension is confined to a quasi-twodimensional geometry, many fascinating crystal structures appear due to the partial restriction of translational degrees of freedom in the third dimension [1][2][3]. In the case of particles interacting with a hard potential the structure greatly depends on their packing efficiency in the confined geometry. One of the first studies in this limit was performed by Pieranski et al., who used nearly hard spherical colloids confined in a wedge-shaped cell. At increasing slit width they found a sequence of transitions that can be represented as:where n denotes the number of crystal layers and △ and □ denote layers with hexagonal and square symmetry, respectively [4]. More detailed investigations since then disclosed that many intermediate phases exist, such as a buckling phase in between 1△ → 2□, a rhombic phase in between n□ → n△, and prismatic, hexagonal close packing (hcp)-like, hcp(100), hcp⊥, and pre-square phases in between n△ → ðn þ 1Þ□ [3,[5][6][7]. All these structures have been verified by computer simulations [8][9][10][11][12][13], and the consistency between experiments and simulations gives us confidence in our understanding of the nature of the transitions for hard spheres.Fewer intermediate phases are found for charged spheres, which interact via long-ranged electrostatic interactions, both with each other and with the walls [14][15][16][17]. Using colloids with κa ¼ 0.79 and 0.37 (where κ is the inverse Debye screening length characterizing the range of the repulsive interactions, and a is the particle radius) we found a phase sequence very similar to Ref. [16]: 1△ → 2□ → 2R → 2△ → 3□ → 3R → 3△ → 4□ → 4R → 4△ (R denotes a rhombic phase) [17]. These observations imply that long-ranged electrostatic interactions play an important additional role in the packing of charged particles.The packing behavior of shape anisotropic particles has also begun to be explored. For nearly hard dimer-shaped particles so-called "side" and "out-of-plane" structures were reported [18,19]. This leads to questions about the effect of confinement on particle orientational order in a system where this effect can be separated from packingdominated changes ...

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“…The charged rods we employed were made of fluorescently labeled silica [24,25] and had a length of 2.29 μm and a diameter of 0.60 μm (see Supplemental Material [26]). They were made hydrophobic by grafting with alkyl chains (C 18 ) and dispersed in the almost index-matching solvent cyclohexyl chloride.…”

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Confinement Induced Plastic Crystal-to-Crystal Transitions in Rodlike Particles with Long-Ranged Repulsion

et al. 2015

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“…Nevertheless, a correction for the resulting lower density would still not account for the total amount of water required to produce the "matchstick" colloids of the observed length. The porosity of these silica rods in a similar system was evidenced by Kuijk et al 12 where they associated the cause with PVP. We suggest that porosity can also be attributed to by the presence of sodium citrate, known to induce porous silica and titanate particle formation.…”

Section: Resultsmentioning

confidence: 73%

Mechanistic Insight into the Synthesis of Silica-Based “Matchstick” Colloids

et al. 2015

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We report an insight into the synthesis of silica-based "matchstick"-shaped colloidal particles, which are of interest in the area of self-propulsion on small length scales. The generation of aqueous emulsion droplets dispersed in an n-pentanol-rich continuous phase and their use as reaction centers allows for the fabrication of siliceous microparticles that exhibit anisotropy in both particle morphology, that is, a "matchstick" shape, and chemistry, that is, a transition-metal oxide-enriched head. We provide a series of kinetic studies to gain a mechanistic understanding and unravel the particle formation and growth processes. Additionally, we demonstrate the ability to select the aspect ratio of the "matchstick" particle in a straightforward manner.

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“…Furthermore, fluorescently labeled rod‐like silica colloids were mixed with SDS and β‐CD to study their co‐assembly with microtubes ( Figure ). Since the rods are longer and their widths are smaller than the tube diameter, the only way for them to be incorporated in the tubes is with their long axis parallel with the tube walls.…”

Section: Resultsmentioning

confidence: 99%

“…The engineering of anisotropic colloidal building blocks has taken a flight over the last decade, yielding a diverse colloidal toolbox that opens up new pathways for the fabrication of advanced functional materials . The continuing sophistication of colloid complexity to direct hierarchical self‐organization is not restricted to the design of colloid shape alone but also includes further functionalization by chemical anisotropy, which provides site‐specific interactions such as in Janus or surface‐patterned particles.…”

Section: Introductionmentioning

confidence: 99%

Self‐Organization of Anisotropic and Binary Colloids in Thermo‐Switchable 1D Microconfinement

Folter

Liu

Jiang

et al. 2014

Part & Part Syst Charact

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Anisotropic and binary colloids self‐assemble into a variety of novel supracolloidal structures within the thermo‐switchable confinement of molecular microtubes, achieving structuring at multiple length scales and dimensionalities. The multistage self‐assembly strategy involving hard colloidal particles and a soft supramolecular template is generic for colloids with different geometries and materials as well as their binary mixtures. The colloidal architectures can be controlled by colloid shape, size, and concentration. Colloidal cubes align in chains with face‐to‐face arrangement, whereas rod‐like colloids predominantly self‐organize in end‐to‐end configurations with their long axis parallel with the long axis of the microtubes. The 1D microconfinement imposed on binary mixtures of anisotropic and isotropic colloids further increases the diversity of colloid‐in‐tube structures. In cube–sphere mixtures, cubes may act as additional confiners, locking in colloidal sphere chains, while a “colloidal Morse code” is generated where rods and spheres alternate in the case of rod–sphere mixtures. The versatile confined colloidal superstructures including their thermoresponsive assembly and disassembly are relevant for the development of stimulus–responsive materials where controlled release and encapsulation are desired.

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Colloidal Silica Rods: Material Properties and Fluorescent Labeling

Cited by 48 publications

References 35 publications

Confinement Induced Plastic Crystal-to-Crystal Transitions in Rodlike Particles with Long-Ranged Repulsion

Confinement Induced Plastic Crystal-to-Crystal Transitions in Rodlike Particles with Long-Ranged Repulsion

Mechanistic Insight into the Synthesis of Silica-Based “Matchstick” Colloids

Self‐Organization of Anisotropic and Binary Colloids in Thermo‐Switchable 1D Microconfinement

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