Nanocomposite polyHIPEs with magnetic nanoparticles: Preparation and heating effect

Hierarchical Macroporous PolyDCPD Composites from Surface-Modified Calcite-Stabilized High Internal Phase Emulsions

High Internal Phase Emulsions (HIPEs) of dicyclopentadiene (DCPD) were prepared using mixtures of surface-modified calcite (mCalcite) and a non-ionic surfactant. Twelve different emulsion formulations were created using an experimental design methodology. Three distinctive levels of the internal phase ratio, the amount of mCalcite loading, and the surfactant were used to prepare the HIPEs. Accordingly, macroporous polyDCPD composites were synthesized by performing ring-opening metathesis polymerization (ROMP) on the HIPEs. The variations in the morphological and physical properties of the composites were investigated in terms of experimental parameters. In the end, five different model equations were derived with a confidence level of 95%. The main and binary interaction effects of the experimental parameters on the responses, such as the average cavity size, interconnecting pore size, specific surface area, foam density, and compression modulus, were demonstrated. The synergistic interaction between the amount of surfactant, the amount of mCalcite loading, and the internal phase ratio appeared to have a dominant role in the average cavity diameter. The solo effect of the internal phase ratio on the interconnecting pore size, foam density, and compression modulus was confirmed. In addition, it was demonstrated that the specific surface area of the composites was mainly changed depending on the amount of mCalcite loading.

Synthesis of Emulsion-Templated Magnetic Porous Hydrogel Beads and Their Application for Catalyst of Fenton Reaction

The pristine Fe₃O₄ nanoparticle (FeNP) is supposed to be a good catalyst of Fenton processes which have shown significant potential for water purification. Herein the magnetic macroporous hydrogel beads, having an open-cell structure, were synthesized by sedimentation polymerization of pristine FeNP stabilized oil-in-water high internal phase emulsions. The effects of the FeNP amount, internal phase fraction, and the costabilizer Tween85 concentration on the structure, such as interconnecting degree, void size, and its distribution of both the surface and inner of the beads, were investigated. With a methyl orange (MO) aqueous solution passing through a chromatography column that was filled with the FeNPs loaded hydrogel beads, the efficiency of these hydrogel beads as catalyst for Fenton reaction to decompose MO in water was tested. The MO was decomposed quickly at the first hour, followed by decomposed gradually in a further 5 h, and the decomposition rate of MO could be up to 99.6% at the end of the test. Moreover, MO decomposition rate remained over 98.2% in six batches which were run in the same beads filled column. The results showed that these FeNPs loaded porous hydrogel beads were reusable and highly efficient supporter for catalysis of Fenton reaction for decomposing organic pollutants in water.

Fabrication of CMC-g-PAM Superporous Polymer Monoliths via Eco-Friendly Pickering-MIPEs for Superior Adsorption of Methyl Violet and Methylene Blue

A series of superporous carboxymethylcellulose-graft-poly(acrylamide)/palygorskite (CMC-g-PAM/Pal) polymer monoliths presenting interconnected pore structure and excellent adsorption properties were prepared by one-step free-radical grafting polymerization reaction of CMC and acrylamide (AM) in the oil-in-water (O/W) Pickering-medium internal phase emulsions (Pickering-MIPEs) composed of non-toxic edible oil as a dispersion phase and natural Pal nanorods as stabilizers. The effects of Pal dosage, AM dosage, and co-surfactant Tween-20 (T-20) on the pore structures of the monoliths were studied. It was revealed that the well-defined pores were formed when the dosages of Pal and T-20 are 9–14 and 3%, respectively. The porous monolith can rapidly adsorb 1,585 mg/g of methyl violet (MV) and 1,625 mg/g of methylene blue (MB). After the monolith was regenerated by adsorption-desorption process for five times, the adsorption capacities still reached 92.1% (for MV) and 93.5% (for MB) of the initial maximum adsorption capacities. The adsorption process was fitted with Langmuir adsorption isotherm model and pseudo-second-order adsorption kinetic model very well, which indicate that mono-layer chemical adsorption mainly contribute to the high-capacity adsorption for dyes. The superporous polymer monolith prepared from eco-friendly Pickering-MIPEs shows good adsorption capacity and fast adsorption rate, which is potential adsorbent for the decontamination of dye-containing wastewater.

Pickering high internal phase emulsions stabilized by worm-like polymeric nanoaggregates

The first worm-stabilized Pickering high internal phase emulsion (HIPE) system was developed to prepare ultra-light porous monoliths.

Macroporous ZnO foams by high internal phase emulsion technique: synthesis and catalytic activity

Zinc(II) oxide nanoparticles were used for the stabilization of dicyclopentadiene (DCPD)-water-based high internal phase emulsions (HIPEs), which were subsequently cured using ring-opening metathesis polymerization (ROMP). The morphology of the resulting ZnO-pDCPD nanocomposite foams was investigated in correlation to the nanoparticle loading and nanoparticle surface chemistry. While hydrophilic ZnO nanoparticles were found to be unsuitable for stabilizing the HIPE, oleic acid coated, yet hydrophobic ZnO nanoparticles were effective HIPE stabilizers, yielding polymer foams with ZnO nanoparticles located predominately at their surface. These inorganic/organic hybrid foam-materials were subsequently calcined at 550 °C for 15 min to obtain inorganic macroporous ZnO foams with a morphology reminiscent to the original hybrid foam, and a specific surface area of 1.5 m(2) g(-1). Longer calcination time (550 °C, 15 h) resulted in a sea urchin like morphology of the ZnO foams, characterized by higher specific surface area of 5.5 m(2) g(-1). The latter foam type showed an appealing catalytic performance in the catalytic wet air oxidation (CWAO) process for the destruction of bisphenol A.

Antagonistic effects between magnetite nanoparticles and a hydrophobic surfactant in highly concentrated Pickering emulsions

Herein we present a systematic study of the antagonistic interaction between magnetite nanoparticles (Fe3O4) and nonionic hydrophobic surfactant in Pickering highly concentrated emulsions. Interfacial tension measurements, phase behavior, and emulsion stability studies, combined with electron microscopy observations in polymerized systems and magnetometry, are used to support the discussion. First, stable W/O highly concentrated emulsions were obtained using partially hydrophobized magnetite nanoparticles. These emulsions experienced phase separation when surfactant is added at concentrations as low as 0.05 wt %. Such phase separation arises from the preferential affinity of the surfactant for the nanoparticle surfaces, which remarkably enhances their hydrophobicity, leading to a gradual desorption of nanoparticles from the interface. W/O emulsions were obtained at higher surfactant concentrations, but in this case, these emulsions were mainly stabilized by surfactant molecules. Therefore, stable emulsions could be prepared in two separate ranges of surfactant concentrations. After polymerization, low-density macroporous polymers were obtained, and the adsorption and aggregation of nanoparticles was analyzed by transmission electron microscopy. The progressive displacement of the nanoparticles was revealed: from the oil-water interface, in which aggregated nanoparticles were adsorbed, forming dense layers, to the continuous phase of the emulsions, where small nanoparticle aggregates were randomly dispersed. Interestingly, the results also show that the blocking temperature of the iron oxide superparamagnetic nanoparticles embedded in the macroporous polymers could be modulated by appropriate control of the concentrations of both surfactant and nanoparticles.