Macro- and near-mesoporous monoliths by medium internal phase emulsion polymerization: A systematic study

Styrene-based polymerised high internal phase emulsions using monomers in the internal phase as co-surfactants for improved liquid chromatography

Poly(styrene-co-divinylbenzene)-based monoliths were prepared from the polymerisation of water-in-monomer high internal phase emulsions, where the water-soluble monomers acrylamide (AAm) or poly(ethylene glycol) diacrylate (PEGDA) (M_w 258) were also included in the 90 vol% internal phase. Both AAm and PEGDA were found to act as co-surfactants, resulting in the obtainment of monoliths with greater homogeneity in some cases. As a result these materials demonstrated significantly improved chromatographic performance for the separation of a standard mixture of proteins using reversed-phase liquid chromatography, in comparison to monoliths prepared with no internal phase monomer. In particular, the columns grafted with PEGDA were capable of separating a more complex mixture consisting of seven components. The inclusion of monomers in the internal phase also allowed for the functionalisation of the monolith's surface where the degree of polymerisation that occurred in the internal phase, which was governed by the monomer content in the internal phase and initiation location, determined whether polymeric chains or a hydrogel were grafted to the surface. A monolith grafted with AAm was also found to be capable of retaining polar analytes as a result of the increase in surface hydrophilicity.

Poly(styrene-co-divinylbenzene)-based monoliths prepared from the polymerisation of water-in-monomer high internal phase emulsions, where water-soluble monomers acrylamide or poly(ethylene glycol) diacrylate (M_w 258) were included in internal phase.

One-Pot Fabrication of Hierarchically Bicontinuous Polystyrene Monoliths with Homogeneous Skeletons and Glycopolymer Surfaces

The hierarchically bicontinuous polystyrene monoliths (HBPMs) with homogeneous skeletons and glycopolymer surfaces are fabricated for the first time based on the medium internal phase emulsion (MIPE) templating method via activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP). The synergistic self-assembly of amphiphilic diblock glycopolymer (ADG) and Pluronic F127 (PF127) at the oil/water interface via hydrogen bonding interaction contributes to the formation of bicontinuous MIPE with deformed neighboring water droplets, resulting in the highly interconnected HBPM after polymerization. There is a bimodal pore size distribution in the HBPM, that is, through pores (150-5000 nm) and mesopores (10-150 nm). The HBPMs as prepared show excellent biocompatibility, homogeneous skeletons, strong mechanical strength, and high bed permeability, overcoming the practical limitations of the second generation of polystyrene (PS) monoliths. Glycoprotein concanavalin A (Con A) can be easily and quickly separated by the HBPM in hydrophilic interaction chromatography (HILIC) mode. These results suggest the HBPMs have great potentials in catalysis, separations, and biomedical applications.

Removal of a cationic dye from aqueous solution by a porous adsorbent templated from eco-friendly Pickering MIPEs using chitosan-modified semi-coke particles

Porous materials prepared from high internal phase emulsions have been attracting much attention in recent years, but two major defects related to the high consumption of organic solvent and surfactants are always difficult to solve.

Tailoring the morphology of poly(high internal phase emulsions) synthesized by using deep eutectic solvents

High internal phase emulsions (HIPEs) are among complex biphasic fluids that expand on the traditional emulsion compositions, for instance, for the preparation of macroporous polymers by emulsion templating. The use of deep eutectic solvents (DESs) as the nonaqueous internal phase of HIPEs allows expanding the conditions at which polymerizations are typically carried out in aqueous HIPEs. Herein, the properties of polystyrene macroporous polymers were studied by polymerizing DES-in-oil HIPEs using choline chloride-based DESs as the internal phase. The effect of DESs’ composition – with amide, alcohol, and carboxylic acid as hydrogen bond donors – and the homogenization method used for the HIPE preparation – vortexing versus high-speed homogenizer – was studied. The stability and droplet size of HIPE precursor, as well as the macroporous structure and the mechanical properties of the synthesized polyHIPEs, are discussed.

Preparation of porous adsorbent via Pickering emulsion template for water treatment: A review

Porous materials as emerging potential adsorbents have received much more attention because they are capable of capturing various pollutants with fast adsorption rate, high adsorption capacity, good selectivity and excellent reusability. In order to prepare porous materials with decent porous structure, Pickering emulsion template method has been proved to be one of the most effective technologies to create pore structure. This paper reviewed comprehensively the latest research progress on the preparation of porous materials from various Pickering emulsions and their applications in the decontamination of pollutants (e.g., heavy metal ions, organic pollutants) and in the oil/water separation. It was expected that the summaries and discussions in this review will provide insights into the design and fabrication of new efficient porous adsorbents, and also give us a better understanding of the subject.

A facile fabrication of porous fluoro-polymer with excellent mechanical properties based on high internal phase emulsion templating using PLA as co-stabilizer

The stability of fluoro-high internal phase emulsion (fluoro-HIPE) systems and fluoro-polyHIPEs’ mechanical strength require further improvement to meet the requirements of future applications. In this study, we used polylactic acid (PLA) as a co-stabilizer to improve the stability of the fluoro-polyHIPE. The effects of concentration and molecular weight of PLA on the pores of the fluoro-polyHIPEs were investigated. The addition of PLA produced a porous material with narrower void size distributions, higher specific surface areas and enhanced mechanical properties compared to the fluoro-polyHIPE material without the additive. The resulting fluoro-polyHIPE showed smaller pore sizes (void diameters ranged from 1–3 μm) and an improved hydrophobic nature (contact angle can reach to 148.6°). The crush strength and Young's modulus values can reach 4.42 and 74.07 MPa, respectively, at a PLA addition of 25 wt% (oil phase composition), representing increases of 246% and 650% over fluoro-polyHIPE without PLA addition. The fluoro-poly-HIPE demonstrated excellent mechanical properties compared to many engineering foams, such as melamine, polystyrene, and even graphite foams. Improvements in the performance of porous fluoropolymer materials will be beneficial for many applications, such as chemical adsorption and separation, etc.

Effect of PLA on the stability of fluorinated-HIPE and size tuning of the resultant fluoro-polyHIPE with enhanced mechanical properties.

Morphology control in polymerised high internal phase emulsion templated via macro-RAFT agent composition: visualizing surface chemistry

A series of polymerized high internal phase emulsion (polyHIPE) materials have been prepared by using a water in oil emulsion stabilized by a macro-RAFT agent, 2-(butylthiocarbonothioylthio)-2-poly(styrene)-b-poly(acrylic acid), acting as a polymeric surfactant.

Macroporous poly(ionic liquid)/ionic liquid gels via CO2-based emulsion-templating polymerization

A high internal phase emulsion composed of ionic liquids and CO₂ serves as a template for producing unprecedented macroporous poly(ionic liquid) gels.

Simultaneous synthesis and chemical functionalization of emulsion-templated porous polymers using nitroxide-terminated macromolecular surfactants

The design of functional 3D macroporous monoliths has become a necessity for a wide range of applications.