High surface area, emulsion-templated carbon foams by activation of polyHIPEs derived from Pickering emulsions.

Carbon foams displaying hierarchical porosity and excellent surface areas of >1400 m2/g can be produced by the activation of macroporous poly(divinylbenzene). Poly(divinylbenzene) was synthesized from the polymerization of the continuous, but minority, phase of a simple high internal phase Pickering emulsion. By the addition of KOH, chemical activation of the materials is induced during carbonization, producing Pickering-emulsion templated carbon foams, or carboHIPEs, with tailorable macropore diameters and surface areas almost triple that of those previously reported. The retention of the customizable, macroporous open-cell structure of the poly(divinylbenzene) precursor and the production of a large degree of microporosity during activation leads to tailorable carboHIPEs with excellent surface areas

Novel macroporous polymers synthesised via new Pickering medium and high internal phase emulsion templates

Imperial Users onl

Demixing, remixing and cellular networks in binary liquids containing colloidal particles

We present a confocal-microscopy study of demixing and remixing in binary liquids containing colloidal particles. First, particle-stabilized emulsions have been fabricated by nucleation and growth of droplets upon cooling from the single-fluid phase. We show that their stability mainly derives from interfacial particles; the surplus of colloids in the continuous phase possibly provides additional stability. Upon heating these emulsions, we have observed the formation of polyhedral cellular networks of colloids, just before the system remixes. Given a suitable liquid-liquid composition, the initial emulsions cross the binary-liquid symmetry line due to creaming. Therefore, upon heating, the droplets do not shrink and they remain closely packed. The subsequent network formation relies on a delicate balance between the Laplace pressure and the pressure due to creaming/remixing. As high concentrations of colloids in the cell walls inhibit film thinning and rupture, the networks can be stabilized for more than 30 minutes. This opens up an avenue for their application in the fabrication of advanced materials.Comment: http://dx.doi.org/10.1039/b918002

Pickering Emulsion and Derived Materials

Particle-stabilized emulsions, today often referred to as Pickering/Ramsden emulsions, are vital in many fields, including personal care products, foods, pharmaceuticals, and oil recovery. The exploitation of these Pickering emulsions for the manufacture of new functional materials has also recently become the subject of intense investigation. While much progress has been made over the past decade, Pickering emulsion still remains a rich topic since many aspects of their behavior have yet to be investigated. The present “Pickering Emulsion and Derived Materials” Special Issue aims to bring together research and review papers pertaining to the recent developments in the design, fabrication, and application of Pickering emulsions. The themes include, but are not limited to: 1. Interactions of colloidal particles confined at fluid interfaces 2. Pickering emulsion-based polymerization 3. Interfacial assembly and emulsion stabilization 4. Rheology of particle laden interfaces and Pickering emulsions 5. Functional materials templated from Pickering emulsion

Emulsion-based supracolloidal materials stabilized by specifically designed branched copolymers

The possible applications of branched copolymers are far reaching because of their various combinations of functionality and architectural diversity. More importantly, the domains and chain-end functionalities of the branched copolymers can be readily varied, via the simple and scalable Strathclyde route, to optimize/tailor the properties of the polymers for a specific application by careful choice of monofunctional monomers, branching monomers, and chain transfer agents. In the present thesis, branched copolymers were utilized as emulsifying agents for the production of oil-in-water emulsion droplets. These emulsion droplets were used as a platform to create novel emulsion-based supracolloidal materials. The chemical composition and architectural structure of the branched copolymers were specifically chosen to create stable emulsions and provide the correct functionalities required for the application. Calcium phosphate (CaP) microcapsules were fabricated by utilizing oil-in-water emulsion droplets, stabilized with branched copolymer, as templates. The branched copolymer was designed to provide a suitable architecture and functionality to produce stable emulsion droplets, and permit the mineralization of CaP at the surface of the oil droplet. These CaP capsules were made fluorescent by post-functionalization of the CaP shell with a fluorescent conjugate. Oil-in-water emulsion droplets stabilized with Laponite clay disc functionalized with pH-responsive branched copolymers were microfluidically spun into supracolloidal fibers. These supracolloidal fibers can be used as a tool to delivery volatile compounds in a time-controlled manner. The dried fibers created were low-weight porous materials. It was also discovered that these supracolloidal fibers can be utilized as a storage material for emulsion droplets, where emulsion droplets are ‘locked’ in the fiber structure under acidic condition, and are released from the fiber upon basification of the system. The release of emulsion droplets from the fiber can be time-controlled by programming the transient acidic pH states of the system by combining a fast acidic promoter with a feedback-driven biocatalytically controlled slow generation of base in a close system.Open Acces

Vinyl Ester Oligomer Crosslinked Porous Polymers Prepared via Surfactant-Free High Internal Phase Emulsions

Using vinyl ester resin (VER) containing styrene (or methyl methacrylate) and vinyl ester oligomer (VEO) as external phase, Pickering high internal phase emulsions (Pickering HIPEs) having internal phase volume fraction of up to 95 vol% were prepared with copolymer particles as sole stabilizer. Polymerizing the external phase of these Pickering HIPEs led to porous polymers (poly-Pickering-HIPEs). Compared to the polystyrene- (PS-) based poly-Pickering-HIPEs which were prepared with mixture of styrene and divinylbenzene (DVB) as crosslinker, the poly-Pickering-HIPEs herein showed much higher elastic modulus and toughness. The elastic modulus of these poly-Pickering-HIPEs increased with increasing the VEO concentration in the external phase, while it decreased with increasing internal phase volume fraction. Increasing VEO concentration in the external phase also resulted in a decrease in the average void diameter as well as a narrow void diameter distribution of the resulting poly-Pickering-HIPEs. In addition, there were many small pores in the voids surface caused by the volume contraction of VER during the polymerization, which suggests a new method to fabricate porous polymers having a well-defined hierarchical pore structure

Saddle-splay modulus of a particle-laden fluid interface

The scaled-particle theory equation of state for the two-dimensional hard-disk fluid on a curved surface is proposed and used to determine the saddle-splay modulus of a particle-laden fluid interface. The resulting contribution to saddle-splay modulus, which is caused by thermal motion of the adsorbed particles, is comparable in magnitude with the saddle-splay modulus of a simple fluid interface.Comment: 10 pages, 2 figure