Deformable Hollow Hybrid Silica/Siloxane Colloids by Emulsion Templating

Zoldesi, C.; Walree, Cornelis A. van; Imhof, Arnout

doi:10.1021/la060101w

Cited by 144 publications

(173 citation statements)

References 37 publications

Supporting

Mentioning

156

Contrasting

Order By: Relevance

“…The 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][5][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 .…”

Section: Introductionmentioning

confidence: 99%

Colloids with valence and specific directional bonding

Wang

Breed

et al. 2012

Nature

969

1,072

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

Colloids with valence and specific directional bonding

Wang

Breed

et al. 2012

Nature

969

1,072

View full text Add to dashboard Cite

show abstract

“…Both of these studies consider bowl-like particles and focus on the columnar phases that they can form. HSCs provide a simpler model for molecular 24,25 and colloidal 26 bowlic liquid crystals as well as being a first, minimal representation of metallic (half-)shells 27 and of the very interesting buckybowlic molecules, concave fragments of fullerene, whose curvature and rigidity may be chemically controlled. 28 (iii) They form an entropy-driven cluster phase, the colloidal analogue of the micellar phase in surfactant solutions, and may constitute a very simple model for the study of arrested states of matter.…”

mentioning

confidence: 99%

Phase behavior of hard spherical caps

Cinacchi

2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

This work reports on the phase behavior of hard spherical caps in the interval of particle shapes delimited by the hard platelet and hemispherical cap models. These very simple model colloidal particles display a remarkably complex phase behavior featuring a competition between isotropicnematic phase separation and clustering as well as a sequence of structures, from roundish to lacy aggregates to no ordinary hexagonal columnar mesophases, all characterized by groups of particles tending to arrange on the same spherical surface. This behavior parallels that one of many molecular systems forming micelles but here it is purely entropy-driven. © 2013 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4822038]The self-assembly of molecular and colloidal systems has always, and nowadays especially, attracted much attention. 1 Recently, in the case of colloids, there has been significant progress in the synthesis of particles of different shape and size as well as in the techniques to visualize the structures they form. 2 These experimental advances offer concrete chances to observe those phase behaviors predicted by theory and numerical simulation; new results from these can in turn stimulate further experimental research. 3 One current example is provided by hard polyhedral particles, to which much numerical and experimental effort is being dedicated. [4][5][6] In theory and simulation, colloidal particles are indeed often assumed to interact through hard-body interactions as these are predominant in directing their packing and shown over the years to be sufficient for the stabilization of a variety of entropy-driven complex fluid phases: nematic (N), 7 smectic, 8 columnar (C), 9 and even cubic gyroid 10 phases can all be obtained in systems of hard-body particles of suitable shape and size.This work considers a special class of hard-body model colloidal particles and examines by numerical simulation their phase behavior featuring both phase separation and aggregation phenomena.The particles are hard spherical caps (HSCs); a preliminary account of their intriguing phase behavior has been given in Ref. 11. Each of these particles is the portion of the surface of a sphere of radius R subtended by an angle θ . The area of this portion is set equal to σ 2 , with σ the unit of length; any particle of this type is thus identified by R* = R/σ (or θ ). By varying R*, hard, generally concave and infinitely thin, particles can be obtained going from the hard platelet, (R* → ∞), through the hard hemispherical cap (R * = 1/ √ 2π ), to the hard sphere (R * = 1/2 √ π) models. It is actually those lens-, bowl-, and vase-like particles that lay in between these limits that are most interesting.HSCs fit current interest for a variety of reasons. These are primarily fundamental but also related to the issues of a) Electronic mail: giorgio.cinacchi@uam.es practical relevance, given, e.g., the wide range of possibilities that nano-sized hollowed particles may offer in catalysis and drug delivery. 12 Several are the viewpoints HSCs can be ...

show abstract

“…Our experimental system consists of hemispherical collapsed shells, which were obtained following the procedure described in ref 17. The only modification was that the dye, rhodamine B-isothiocyanate (RITC), was incorporated in the shell during the coating step.…”

mentioning

confidence: 99%

Phase Behavior and Structure of a New Colloidal Model System of Bowl-Shaped Particles

et al. 2010

Self Cite

View full text Add to dashboard Cite

We study the phase behavior of bowl-shaped (nano)particles using confocal microscopy and computer simulations. Experimentally, we find the formation of a wormlike fluid phase in which the bowl-shaped particles have a strong tendency to stack on top of each other. However, using free energy calculations in computer simulations, we show that the wormlike phase is out-ofequilibrium and that the columnar phase is thermodynamically stable for sufficiently deep bowls and high densities. In addition, we employ a novel technique based on simulated annealing to predict the crystal structures for shallow bowls. We find four exotic new crystal structures and we determine their region of stability using free energy calculations. We discuss the implications of our results for the development of materials consisting of molecular mesogens or nanoparticles.KEYWORDS Nanobowls, crystal structures, computer simulations, phase diagram, columnar liquid crystals I n recent years, a whole variety of bowl-shaped nanoparticles and colloids have been synthesized and characterized, 1-6 and possible applications of these systems have been put forward. Most of these applications are of a single particle nature, such as a nanocontainer, 4 or for metallic nanobowls depend on the tendency of these particles to form foamlike structures upon aggregation. Applications of the latter kind include superhydrophobic 5 and infrared-blocking 3 coatings. Metallic nanoparticles can be stabilized, for example, by applying a capping layer, 7 which should prevent aggregation and thus reveal the natural tendency of bowl-shaped particles to form stacks or columns. In the molecular liquid crystal community, this tendency has been thought to decrease the number of defects in columnar phases, which is important if these columnar phases are to replace 8 the crystalline ferroelectrics (materials with a permanent electric polarization) in (future) applications, such as sensors, electromechanical devices, and nonvolatile memory. 9 Several bowl-shaped molecules have already been synthesized and found to form columnar phases. 10 In addition, buckybowlic molecules, that is, fragments of C 60 whose dangling bonds have been saturated with hydrogen atoms, have been shown to crystallize in a columnar fashion. 11-15 An aligned phase of metallic nanobowls could also be a promising novel material, since the individual particles have strongly anisotropic optical properties. 1,3 However, no systematic experimental studies of the structure of nanobowls in solution exist to our knowledge, and therefore it remains an open question whether or not bowlshaped nanoparticles and colloids can form stacks and ordered structures. This issue is also not easily resolved using theory or simulations as it is difficult to model the complicated particle shape, although a recent simulation study 8 exists in which the attractive-repulsive Gay-Berne potential was generalized to a bowl-shaped particle. In another very recent simulation study 16 of hard contact lenses (infinitely thin, shall...

show abstract

Deformable Hollow Hybrid Silica/Siloxane Colloids by Emulsion Templating

Cited by 144 publications

References 37 publications

Colloids with valence and specific directional bonding

Colloids with valence and specific directional bonding

Phase behavior of hard spherical caps

Phase Behavior and Structure of a New Colloidal Model System of Bowl-Shaped Particles

Contact Info

Product

Resources

About