Study of the formation of the open-cellular morphology of poly(styrene/divinylbenzene) polyHiPE materials by cryo-SEM
TL;DR: In this article, the formation of the interconnected morphology of open-cell styrene/divinylbenzene (DVB) PolyHIPE copolymers has been studied by scanning electron microscopy on frozen HIPE samples at different stages of polymerisation, a technique known as cryo-SEM.
Abstract: The formation of the interconnected morphology of open-cell styrene/divinylbenzene (DVB) PolyHIPE copolymers has been studied by scanning electron microscopy on frozen HIPE samples at different stages of polymerisation, a technique known as cryo-SEM. The transition from discrete emulsion droplets to interconnected cells was observed to occur around the gelpoint of the polymerising system. This would suggest that the formation of holes between adjacent cells is due to the contraction of the thin monomeric films on conversion of monomer to polymer, as a result of the higher density of the latter.
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TL;DR: The use of high internal phase emulsions as templates to create highly porous materials (PolyHIPEs) is described in this article, where the void fraction is very high and can reach levels of 0.99.
653 citations
TL;DR: In this article, the authors cover recent work in this area, focusing on: the preparation of such materials from new precursors and via novel approaches; the chemical modification of existing materials; and the application of the resulting porous structures in diverse areas of science and technology.
Abstract: Porous materials are currently of great scientific as well as technological interest. A strategy that is increasingly employed to prepare highly porous and well defined macroporous polymers is emulsion templating, whereby the droplets of a high internal phase emulsion are used to create pores in a solid material by curing or polymerization of the emulsion continuous phase. This Feature Article covers recent work in this area, focusing on: the preparation of such materials from new precursors and via novel approaches; the chemical modification of existing materials; and the application of the resulting porous structures in diverse areas of science and technology.
364 citations
TL;DR: It is proposed that this two-step process to create CNC HIPEs relies on a swelling process of the droplets that does not desorb the CNCs from the interface, decreasing the coverage ratio of theDroplets and leading to coalescence.
364 citations
TL;DR: In particular, relatively polar solvents that are able to transport water through the emulsion continuous phase (Ostwald ripening) are shown to produce much lower surface areas than analogous resins prepared by homogeneous solution polymerization of divinylbenzene.
Abstract: Poly(divinylbenzene) emulsion-derived (PolyHIPE) solid foams prepared with porogens (toluene, chlorobenzene, (2-chloroethyl)benzene, 1,2-dichlorobenzene, and 1-chloro-3-phenylpropane) in the oil phase have morphologies and surface areas that are strongly influenced by the nature of the porogen. For the case where the surfactant employed is Span 80, we show that the solid foam structure depends on (i) the ability of the solvent to swell the growing network, (ii) the solvent polarity, and (iii) the ability of the solvent to adsorb at the emulsion interface. In particular, relatively polar solvents that are able to transport water through the emulsion continuous phase (Ostwald ripening) are shown to produce much lower surface areas than analogous resins prepared by homogeneous solution polymerization of divinylbenzene in the presence of the solvent in question alone. The influence of Ostwald ripening is further suggested by the observation that surface area decreases with increasing emulsion aqueous phase co...
295 citations
TL;DR: Recently, a series of new monomers and polymerization mechanisms has been applied to the templating of high internal phase emulsions (HIPEs) providing a route to hierarchically porous materials with a range of functionalities and applications.
Abstract: Recently, a series of new monomers and polymerization mechanisms has been applied to the templating of high internal phase emulsions (HIPEs) providing a route to hierarchically porous materials with a range of functionalities and applications The high degree of control over the pore size is another attractive feature of these materials Usually, the continuous phase contains monomers, the droplet phase is used to template the large, primary pores, which are interconnected by secondary pores The addition of nonpolymerizable components to the continuous phase can result in phase separation during polymerization and tertiary pores Applications include polymer supports for catalysis and synthesis, separation and filtration, cell culture media, enzyme supports, and structural and isolation applications
276 citations
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TL;DR: In this paper, the authors extended their earlier work to include oil phases comprised of 100% styrene or 100% divinylbenzene and evaluated the effects of these phases on the microstructure and compressive properties of open cell foams.
Abstract: High internal phase emulsions (HIPEs) provide an attractive route to open cell foams. In this paper, we extend our earlier work to include oil phases comprised of 100% styrene or 100% divinylbenzene. In addition, we have evaluated the effects oil-soluble versus water-soluble polymerization initiators, aqueous-phase salt concentrations, and the degree of cross-linking on the microstructure and compressive properties. Foam cell sizes were found to be inversely related surfactant level, relatively insensitive to increases in the monomer levels, but greatly affected by salt concentration. The best textured foams generally had the best formed cells and the most open microstructure.
203 citations
TL;DR: In this paper, polyhype polymers with completely interconnected cellular structures of overall very low density are prepared by polymerization of the styrene-divinylbenzene continuous oil phase of a number of high internal phase emulsions (HIPE).
Abstract: Polyhype polymers with completely interconnected cellular structures of overall very low density are prepared by polymerization of the styrene-divinylbenzene continuous oil phase of a number of high internal phase emulsions (HIPE). By adjustment of the level of crosslinker and by use of eitheir a precipitating porogen or a solvating porogen in the comonomer oil phase, a secondary pore structure is generated within the cell «walls» of the polymers. Their surface area and their pore volume are determined
194 citations
TL;DR: Polymerisation en emulsion d'un melange styrene-divinylbenzene-dodecane-eau is described in this article, where the structure de la mousse (SEM) is considered.
Abstract: Polymerisation en emulsion d'un melange styrene-divinylbenzene-dodecane-eau. Etude de la structure de la mousse (SEM). Influence de la composition de la phase huile (addition d'un hydrocarbure aliphatique)
82 citations