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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: 17
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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: 387
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