Polymeric foams prepared from polymerizing high internal-phase emulsions (polyHIPEs) provide several distinct advantages over conventional polymer resins for applications in separations as well as ...chemical transformations, most notably reliance on convective rather than diffusive mass transport. Elimination of the slow diffusion through pores of a typical macroporous resin bead allows for higher throughputs to be achieved using polyHIPE resins. This review will discuss recent examples of polyHIPE materials used in separations applications (metal complexation, ion-exchange, protein purification, chromatography, and oil/water separation) as well as supports for various catalysts (small molecules, nanoparticles, and enzymes) for chemical-transformation applications.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
This study investigates the use of submicron polymeric particles with varying crosslinking densities as the sole stabilizer for producing Polymerized High Internal Phase Emulsions (PolyHIPE). We ...establish a direct correlation between the crosslinking density and the hydrophilicity of the polymer particles. The hydrophilicity of these particles significantly influences the morphology and rheology of HIPEs. These differences manifest as various morphological variations in the resulting PolyHIPE templates. It was discovered that by increasing the crosslinker weight percentage in the particles from 0 % to 100 %, PolyHIPEs with semi-open, open, and closed porous structures can be obtained. Furthermore, non-crosslinked particles were observed to dissolve in the continuous phase, acting as macromolecular surfactants that generate small pores akin to surfactant-stabilized structures in PolyHIPE. These findings offer fresh insights into the relationship between particle localization at the interface, HIPE rheology, and the formation of pore throats in Pickering PolyHIPEs, leading to the creation of either closed or open porous networks. Additionally, interfacial rheological results demonstrate that particles synthesized with varying monomer-to-crosslinker ratios exhibit different interfacial elasticities, which are linked to PolyHIPE morphology.
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•Particle hydrophilicity affects HIPE morphology, viscosity, and the resulting PolyHIPE morphology.•PolyHIPEs with either a closed or open cellular morphology can be obtained by adjusting the hydrophilicity of the particles.•Dissolved particles act as macromolecular surfactants, resulting in PolyHIPEs with small but semi-open pores.•HIPE viscosity can serve as an indicator of the openness of PolyHIPEs.•The openness of PolyHIPEs decreases when dilatational interfacial elasticity decreases due to a reduction in hydrophilicity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Polymerized high internal phase emulsions (PolyHIPEs) are porous polymers made using an emulsion template. Our group has previously shown that polydimethylsiloxane (PDMS) polyHIPEs prepared using a ...thiol-ene crosslinking reaction could obtain a maximum total porosity of ∼63%. Attempting to increase total porosity by increasing the volume fraction dispersed phase resulted in collapse of the porous material due to the soft nature of PDMS. In this work, polymethylvinylsiloxane (PMVS) was synthesized to impart high crosslinking density in the network. This polymer can be blended with divinyl-PDMS in the continuous phase to obtain a large range of storage moduli (25–900 kPa) in the final polyHIPEs with higher total porosity (74–77%). Finally, the use of these PDMS PolyHIPEs as separation media for oil/water mixtures has been demonstrated.
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•Preparation of highly porous PDMS polyHIPEs is difficult due to pore collapse.•Increasing the crosslinking density can maintain open-cell porosity above 74%.•The materials are still elastomeric and soft, with storage moduli below 300 kPa.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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Elastomeric materials combining multiple properties within a single composite are highly desired in applications including biomaterials interfaces, actuators, and soft robotics. High ...spatial resolution is required to impart different properties across the composite for the intended application, but many techniques used to prepare these composites rely on multistep and complex methods. There is a need for the development of simple and efficient platforms to design layered composite materials. Here, we report the synthesis of horizontally- and vertically-patterned composites consisting of PDMS-based polymerized high internal phase emulsion (polyHIPE) porous elastomers and PDMS/PEG hydrogels. Composites with defined interfaces that were mechanically robust were prepared, and rheological analysis of the polyHIPE and hydrogel layers showed storage moduli values of ∼ 35 kPa and 45 kPa respectively. The compressive Young’s Modulus and maximum strain of the polyHIPEs were dependent on the thiol to ene ratio in the formulation and obtained values ranging from 6 to 25 kPa and 50–65% respectively. The mechanical properties, total porosity of the polyHIPE, and swelling ratio of the hydrogel were unaffected by the patterning technique compared to non-patterned controls. PolyHIPE-hydrogel composite materials having up to 7-different horizontally pattered layers could be prepared that could expand and contract up hydration and drying.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•PVBC-g-PCE is prepared by UV-initiated polymerization from PolyHIPE for recovery of Li+.•PVBC-g-PCE has strong physical strength, high density of sites, and macroporous structure.•PVBC-g-PCE shows ...excellent adsorption kinetics, binding capacity, and specific selectivity.•Chemisorption via host-guest interaction may be main driving force to selective recognition.
It is highly desirable to develop an efficient adsorbent with large capacity, high selectivity and fast kinetics to recovery virtually inexhaustible lithium ion (Li+) resources from salt lake brine. In this work, 2-(allyloxy) methylol-12-crown-4 ether (2AM12C4) functionalized polymer brushes (PVBC-g-PCE) from macroporous polymeric high internal-phase emulsion (PolyHIPE) using UV-initiated surface polymerization are synthesized for selectively recovery of Li+. PVBC-g-PCE possesses the advantages of strong physical strength, high density of accessible binding sites, and the size of highly permeatable voids and interconnecting pores is about 8.0–18 µm and 3.3–4.8 µm, respectively, which is a favorable adsorbent for specific capture Li+. PVBC-g-PCE has a maximum capacity at pH 6.0, and the pH-dependent adsorption amount suggests the grafted polymer brushes of 2AM12C4 is the driving force to enhance binding performance. PVBC-g-PCE has a fast adsorption equilibrium within 45 min, and the kinetic results are well-described by the pseudo-second-order model, indicating the specific host-guest interaction between functionalized 2AM12C4 and Li+ is the main adsorption mechanism. Moreover, the maximum monolayer binding amount of PVBC-g-PCE is 4.43 mg g−1, and the strong affinity in the presence of four kinds of interfering ions (i.e. Na+, K+, Mg2+, and Ca2+) is also observed, which can also be proved by the high relative selectivity separation coefficient (αr) between 3.16 and 7.98. It is expected that this PVBC-g-PCE with abundant easy-to-access specific recognition sites can be applied as a promising adsorbent for effective separation of Li+.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Due to intermediate hydrophobicity of methyl methacrylate (MMA) monomer in water, it is difficult to prepare its stable water in oil high internal phase emulsion (HIPE). Moreover, the addition of ...fully hydrophilic co-monomer such as 2-hydroxyethyl methacrylate (HEMA) in MMA monomer makes it further troublesome to stabilize these emulsions. This paper addresses the preparation of such type of difficult to prepare emulsions via addition of an amphiphilic fluorinated di-block copolymer (FDB), poly(2-dimethylamino)ethylmethacrylate-b-poly(trifluoroethyl methacrylate) (PDMAEMA-b-PTFEMA) as stabilizer. Interestingly, HEMA and/or HFBA (hexa fluorobutyl acrylate) as co-monomers were successfully added to impart some special properties such as thermodynamic stability, desired amphiphilicity to the final polyHIPEs. Fluorinated blocks in FDB anchored well at oil/water interface of HIPE, offering enough hydrophobicity to the comparatively hydrophilic monomers and in turn providing resistance against coalescence. MMA polyHIPEs were found to be fully hydrophobic just by replacing HEMA co-monomer with HFBA. Due to superb inherent hydrophobic nature of fluorine atoms, MMA-HFBA polyHIPEs showed remarkable water contact angle of 139°. Furthermore, the addition of fluorinated co-monomer in MMA based HIPEs significantly improved thermal stabilities of these materials with improvement in degradation temperature from 305 °C to 360 °C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Modified cellulose nanocrystals stabilize water-in-oil high internal phase emulsion.•Polymerization of the continuous phase lead to open-cell monoliths.•Mechanical properties do not vary with the ...solid foam cell size.•For low density foams, the Gibson and Ashby model applies to the obtained monoliths.
Porous materials were produced based on high internal phase emulsions (HIPE) formulation stabilized by modified cellulose nanocrystals (CNCs). CNCs were first modified with bromoisobutyryl bromide and used as Pickering emulsion stabilizers to formulate highly concentrated inverse emulsions. Solid foams with an open porosity were successively produced by free radical polymerization of styrene/divinylbenzene continuous phase. The final materials were characterized regarding their cell size distribution, porosity and mechanical properties and then compared with well-known styrene/DVB polyHIPE stabilized either with usual surfactants or solid particles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Adsorbents reported for liquid phase decontamination under both aqueous and non-aqueous media are all dispersed phase sorbents that further require a tedious separation step post adsorption. Herein, ...a monolith, highly porous, and mechanically robust scaffold was synthesized for the adsorption of pollutants from both aqueous and non-aqueous media with facile separation and regeneration. Methylcellulose-tannic acid complex particles were prepared and systematically decorated on the surface of interpenetrating polymer network (IPN) scaffold via Pickering emulsion. Due to the surface coating of the particles, plausible amphiphilic adsorption of quinoline (QUI) and methylene blue (MB) was achieved from fuel and water, respectively. The hydroxyl (OH-) and carboxyl (COOH-) groups of tannic acid, alginate, and polyacrylic acid created hydrogen bonding, electrostatic interaction, acid-base interaction, and π-π stacking. Maximum adsorption capacity of 791.17 mg/g MB and 460.92 mg/g QUI was recorded with facile separation, excellent adsorbent regeneration, and reusability. Although both followed the pseudo-second-order adsorption kinetic model, a different mechanism was identified to govern the adsorption under aqueous and non-aqueous environment i.e. only the surface particles were active for QUI adsorption while the scaffold was also involved for MB adsorption.
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•Monolith sorbent for both aqueous and non-aqueous media and easy regeneration.•High MC% resulted in stable emulsion and highly porous, resilient scaffold.•Amphiphilic colloidal particles act as both emulsifier and adsorption sites.•Efficient adsorption of contaminants from both water and n-heptane.•Different adsorption mechanisms in aqueous and non-aqueous media.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•PVBC-g-PGMA-CE is prepared by polyHIPEs using surface-initiated ATRP and postsynthetic modification.•PVBC-g-PGMA-CE with macroporous structure and high density of sites is used to selective ...extraction Li+.•PVBC-g-PGMA-CE shows quick adsorption kinetics, high adsorption capacity, and excellent selectivity.•The equilibrium and kinetic studies indicated a monolayer and chemisorption process via host-guest interaction.
For the efficient extraction of lithium ions (Li+) from salt-lake brines, adsorbents with high adsorption capacity, fast equilibrium rate, and excellent selectivity are urgently needed. Herein, aminoethyl benzo-12-crown-4 (2AB12C4) functionalized polymer brushes (PVBC-g-PGMA-CE) from macroporous and polymeric high internal-phase emulsion (polyHIPEs) using surface-initiated ATRP and postsynthetic modification was constructed for selective recovery of Li+. Owing to the macroporous structure and high density of binding sites of PVBC-g-PGMA-CE, the equilibrium time was 50 min, and the maximum adsorption capacity was 4.76 mg g−1 at 25 °C. The equilibrium and kinetic studies indicated a monolayer and chemisorption process via homogeneous sites and host-guest interaction. Attributed to the size sieving effect and affinity difference, PVBC-g-PGMA-CE possessed the highest the binding capacities towards Li+ in the competitive adsorption, and the relative selective separation factors (αr) for coexisting ions (i.e. Ca2+, Mg2+, Na+ and K+) were all higher than 4.67. The adsorption amount of PVBC-g-PGMA-CE towards Li+ after five regeneration cycles was 97.30% of the first cycle. The results demonstrated that the developed PVBC-g-PGMA-CE was the promising adsorbent for the efficient and selective recovery of Li+.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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