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Abstract: In this article, we report a series of functionalizedpolyacetylene-type networks formed by chain-growth insertioncoordination polymerization in high internal phase emulsions(HIPEs). All polymerized HIPEs (polyHIPEs) contain a hierarchi-cally structured, 3D-interconnected porous framework consistingof a micro-, meso- and macropore system, resulting in exception-ally high specific surface areas (up to 1055 m2·g−1) and totalporosities of over 95%. The combination of π-conjugated andhierarchically porous structure in one material enabled the use ofthese polyacetylene polyHIPEs as adsorptive photocatalysts for theremoval of chemical contaminants from water. All polyacetylenepolyHIPEs demonstrated high efficiency in the adsorption ofbisphenol A from water (up to 48%) and the subsequentphotocatalytic degradation. Surprisingly, high adsorption capacitydid not affect the photocatalytic efficiency (up to 58%). On the contrary, this dual function seems to be very promising, as somepolyacetylene polyHIPEs almost completely removed bisphenol A from water (97%) through the adsorption-photooxidationmechanism. It also appears that the presence of polar functional side groups in the polyacetylene backbone improves the contact ofthe polyacetylene network with the aqueous bisphenol A solution, which can thus be more easily adsorbed and subsequentlyoxidized, compensating for the lower specific surface area of some networks, namely, 471 and 308 m2·g−1 in the case of 3-ethynylphenol- and 3-ethynylaniline-based polyacetylene polyHIPEs, respectively.
Keywords: polyacetylenes, emulsion-templating, π-conjugated networks, macroporous polymers, heterogeneous photocatalysis
Published in DKUM: 29.08.2024; Views: 73; Downloads: 64
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Abstract: Highly porous metal oxide−polymer nanocomposites are attracting considerable interest due to their unique structural and functional features. A porous polymer matrix brings properties such as high porosity and permeability, while the metal oxide phase adds functionality. For the metal oxide phase to perform its function, it must be fully accessible, and this is possible only at the pore surface, but functioning surfaces require controlled engineering, which remains a challenge. Here, highly porous nanocomposite beads based on thin metal oxide nanocoatings and polymerized high internal phase emulsions (polyHIPEs) are demonstrated. By leveraging the unique properties of polyHIPEs, i.e., a three-dimensional (3D) interconnected network of macropores, and high-precision of the atomic-layer-deposition technique (ALD), we were able to homogeneously coat the entire surface of the pores in polyHIPE beads with TiO$_2$-, ZnO-, and Al$_2$O$_3$-based nanocoatings. Parameters such as nanocoating thickness, growth per cycle (GPC), and metal oxide (MO) composition were systematically controlled by varying the number of deposition cycles and dosing time under specific process conditions. The combination of polyHIPE structure and ALD technique proved advantageous, as MO-nanocoatings with thicknesses between 11 ± 3 and 40 ± 9 nm for TiO$_2$ or 31 ± 6 and 74 ± 28 nm for ZnO and Al$_2$O$_3$, respectively, were successfully fabricated. It has been shown that the number of ALD cycles affects both the thickness and crystallinity of the MO nanocoatings. Finally, the potential of ALD-derived TiO$_2$-polyHIPE beads in photocatalytic oxidation of an aqueous bisphenol A (BPA) solution was demonstrated. The beads exhibited about five times higher activity than nanocomposite beads prepared by the conventional (Pickering) method. Such ALD-derived polyHIPE nanocomposites could find wide application in nanotechnology, sensor development, or catalysis.
Keywords: nanovlakna, aerosoli, filtracija, emulsion-templating, macroporous polymers, atomic-layer-deposition
Published in DKUM: 15.04.2024; Views: 249; Downloads: 24
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Abstract: This paper describes a Fabry-Perot sensor-based measuring system for measuring fluid composition in demanding industrial applications. The design of the sensor is based on a two-parametric sensor, which enables the simultaneous measurement of temperature and refractive index (RI). The system was tested under real industrial conditions, and enables temperature-compensated online measurement of emulsion concentration with a high resolution of 0.03 Brix. The measuring system was equipped with filtering of the emulsion and automatic cleaning of the sensor, which proved to be essential for successful implementation of a fiber optic RI sensor in machining emulsion monitoring applications.
Keywords: optical fiber sensors, Fabry–Pérot interferometer, refractive index, temperature, emulsion concentration
Published in DKUM: 06.02.2024; Views: 336; Downloads: 32
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Abstract: The effect of adding a comonomer to dicyclopentadiene in high internal phase emulsions (HIPEs) on the properties of ring-opening metathesis polymerisation (ROMP) derived polyHIPEs has been investigated. With this aim, dicylopentadiene was copolymerised with norbornene in surfactant stabilized high internal phase emulsions. Morphological, mechanical and thermal properties of the resulting materials were investigated with regard to the monomer ratio. The interconnected pore structure was observed for the resulting poly(dicylopentadiene-co-norbornene) polyHIPEs. Furthermore, the new polyHIPE copolymers were found to have an improved thermal stability compared to the poly(dicylopentadiene) homopolymer.
Keywords: mechanical properties, emulsion templating, polyHIPE, dicyclopentadiene, norbornene
Published in DKUM: 07.08.2017; Views: 1657; Downloads: 414
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Abstract: Poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) monolithic supports were prepared by radical polymerisation of the continuous phase of water in oil high internal phase emulsions. Morphology of monolithic materialswas studied by scanning electron microscopy and mercury intrusion porosimetry. The ratio of phase volume and the degree of crosslinking influenced the void size and pore size distribution of resulting polymers. Void sizes between 1 and 10 m were observed and average pore sizes around 100nm. Polymers with 60, 75, 80 and 90% pore volume were prepared and even samples with highest pore volume showed good mechanical stability. They were modified to bear weak-anion exchange groups and tested on the separation of standard protein mixture containing myoglobin, conalbumine and trypsin inhibitor. Good separation was obtained in a very short time similar to the separation obtained by commercial methacrylate monoliths. However, higher dispersion was observed. Bovine serum albumin dynamic binding capacity for monolith with 90% porosity was close to 9 mg/ml.
Keywords: organic chemistry, methacrylate monoliths, preparation, emulsion polymerization, high porosity, high mechanical stability, polymer chromatographic supports, monolithic methacrylate supports, protein separation
Published in DKUM: 01.06.2012; Views: 2570; Downloads: 71
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