Bicontinuous emulsions stabilized solely by colloidal particles

Abstract

Recent large-scale computer simulations suggest that it may be possible to create a new class of soft solids, called 'bijels', by stabilizing and arresting the bicontinuous interface in a binary liquid demixing via spinodal decomposition using particles that are neutrally wetted by both liquids. The interfacial layer of particles is expected to be semi-permeable; hence, if realized, these new materials would have many potential applications, for example, as micro-reaction media. However, the creation of bijels in the laboratory faces serious obstacles. In general, fast quench rates are necessary to bypass nucleation, so that only samples with limited thickness can be produced, which destroys the three-dimensionality of the putative bicontinuous network. Moreover, even a small degree of unequal wettability of the particles by the two liquids can lead to ill-characterized, 'lumpy' interfacial layers and therefore irreproducible material properties. Here, we report a reproducible protocol for creating three-dimensional samples of bijel in which the interfaces are stabilized by essentially a single layer of particles. We demonstrate how to tune the mean interfacial separation in these bijels, and show that mechanically, they indeed behave as soft solids. These characteristics and their tunability will be of great value for microfluidic applications.

Microstructural tunability of co-continuous bijel-derived electrodes to provide high energy and power densities

“…Bijels were prepared by spinodal decomposition in a binary mixture of 2,6-lutidine and water, and arrested by interfacial jamming of colloidal silica particles 697 nm in diameter with a coefficient of variance of 2.6%. 16 The colloid volume fraction was varied from 0.014 to 0.040 to adjust the characteristic domain size, x. Bijels were transformed into bicontinuous polymer scaffolds by selectively polymerizing the lutidine phase with a hydrophobic monomer (1,6 hexanedioldiacrylate) mixed with a photoinitiator (Darocur 1173). 18 Nickel was then electrolessly deposited on the polymer scaffold to create a 1 mm thick coating on the outer surface of the polymer.…”

“…16,24 Briey, 32 mg of nickel chloride hexahydrate and 50 mg of urea were added to 20 mL of water, and transferred to an autoclave reactor along with the porous nickel scaffold. The reactor was heated to 180 C for the desired time, and then allowed to cool down to room temperature.…”

“…15 Bijels are formed through arrested spinodal decomposition of a binary liquid mixture by neutrally wetting colloidal particles. 16 During phase separation, the particles sequester to the uid-uid interface and become jammed once the interfacial area is sufficiently reduced to just accommodate them. The resulting non-equilibrium material consists of two uniform, interpenetrating and continuous uid domains separated by a colloid monolayer.…”

Self-assembling knots of controlled topology by designing the geometry of patchy templates

“…For instance, colloidal scientists and soft matter physicists have explored the feasibility of self-assemblying extended photonic crystals and other metamaterials by designing patchy particles of increasingly complex surface activity [1][2][3][4] , by exploiting the shape anisotropy of convex polyhedrical colloids 5,6 or by choosing to disperse particles into complex fluids such as binary fluids or liquid crystals [7][8][9][10] . The resulting interparticle interactions are in general highly non-trivial and can promote the formation of crystals, glasses, gels and so on, often with tunable physical properties 11 .…”

Hexagulation numbers: the magic numbers of equal spheres on triply periodic minimal surfaces

“…For cubic symmetry in particular, we unravel these magic numbers in terms of a similar number, the hexagulation number H, which is the main result of the present paper. Future applications of such regular arrangements are to construct complex membranes using the concepts of bijels, colloidosomes, and polymersomes [30][31][32][33].…”