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Journal article(2020)
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João Nunes-Pereira, Pedro Costa, Liliana Fernandes, Estela O. Carvalho, Margarida M. Fernandes, Sónia A.C. Carabineiro, Josephus G. Buijnsters, Carmen R. Tubio, Senentxu Lanceros-Mendez
Environmentally resilient antimicrobial coatings are becoming increasingly required for a wide range of applications. For this purpose, nanocomposite thin films of poly(vinylidene fluoride) (PVDF) filled with several types of functionalized nanodiamonds (NDs) were processed by solvent casting. The effects of ND inclusion and functionalization in their morphological, structural, optical, thermal, and electrical properties were evaluated taking into account the type of the nanofiller and a concentration up to 2 wt %. The morphology, structure, and thermal features of the polymer matrix are governed by the processing conditions, and no noticeable changes occurred due to the presence of the ND fillers. The polymer crystallized mainly in the α phase with a crystallinity of ≈60%. In turn, the optical transmittance from 200 to 800 nm and the dielectric constant effectively depended on the ND type and content. The inclusion of the ND particles effectively provided antimicrobial properties to the films, which depended on the ND functionalization. This study thus shows that the incorporation of functionalized NDs into PVDF allows the development of antimicrobial coatings with tailorable optical and dielectric properties, which could be of great importance to face nowadays pandemic crisis scenario.
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Environmentally resilient antimicrobial coatings are becoming increasingly required for a wide range of applications. For this purpose, nanocomposite thin films of poly(vinylidene fluoride) (PVDF) filled with several types of functionalized nanodiamonds (NDs) were processed by solvent casting. The effects of ND inclusion and functionalization in their morphological, structural, optical, thermal, and electrical properties were evaluated taking into account the type of the nanofiller and a concentration up to 2 wt %. The morphology, structure, and thermal features of the polymer matrix are governed by the processing conditions, and no noticeable changes occurred due to the presence of the ND fillers. The polymer crystallized mainly in the α phase with a crystallinity of ≈60%. In turn, the optical transmittance from 200 to 800 nm and the dielectric constant effectively depended on the ND type and content. The inclusion of the ND particles effectively provided antimicrobial properties to the films, which depended on the ND functionalization. This study thus shows that the incorporation of functionalized NDs into PVDF allows the development of antimicrobial coatings with tailorable optical and dielectric properties, which could be of great importance to face nowadays pandemic crisis scenario.
C60 Nanocomposites: Convergence of Feeding Formulations into a Similar Nanomorphology
Journal article(2017)
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Hugo Gaspar, Paulo Teixeira, Steven Parnell, Stephen M. King, Nigel Clarke, Jose A. Covas, Gabriel Bernardo, Raquel Santos, Liliana Fernandes, Loic Hilliou, Michael P. Weir, Andrew J. Parnell, Kerry J. Abrams, Christopher J. Hill, Wim Bouwman
We investigated the effect of the feeding formulation (premixed powders of pure components versus solvent-blended mixture) of polystyrene–C60 composites on the dispersion and reagglomeration phenomena developing along the barrel of a twin-screw extruder. The dispersion of C60 in the PS matrix is studied over different length scales using a combination of optical microscopy, spin-echo small-angle neutron scattering (SESANS), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS). When a solvent-blended mixture is used as the feeding formulation, the inlet material contains essentially molecularly dispersed C60 as revealed by the nanodomains with very small phase contrast. However, C60 reagglomeration occurs along the extruder, creating a morphology still containing only nanodomains but with much higher phase contrast. In the case of mixed powders, the material evolves from the initial macroscopic mixture of pure polystyrene and C60 into a composite simultaneously containing micro- and nanoaggregates of C60 as well as C60 molecularly dispersed in the matrix. Our results show that the two different initial feeding formulations with widely different initial morphologies converge along the extruder, through opposite morphological pathways, into a similar final nanomorphology which is dictated by the interplay between the thermodynamics of the system and the flow. Correlations between the morphological evolution along the extruder and the thermorheological properties of the composites are identified.
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We investigated the effect of the feeding formulation (premixed powders of pure components versus solvent-blended mixture) of polystyrene–C60 composites on the dispersion and reagglomeration phenomena developing along the barrel of a twin-screw extruder. The dispersion of C60 in the PS matrix is studied over different length scales using a combination of optical microscopy, spin-echo small-angle neutron scattering (SESANS), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS). When a solvent-blended mixture is used as the feeding formulation, the inlet material contains essentially molecularly dispersed C60 as revealed by the nanodomains with very small phase contrast. However, C60 reagglomeration occurs along the extruder, creating a morphology still containing only nanodomains but with much higher phase contrast. In the case of mixed powders, the material evolves from the initial macroscopic mixture of pure polystyrene and C60 into a composite simultaneously containing micro- and nanoaggregates of C60 as well as C60 molecularly dispersed in the matrix. Our results show that the two different initial feeding formulations with widely different initial morphologies converge along the extruder, through opposite morphological pathways, into a similar final nanomorphology which is dictated by the interplay between the thermodynamics of the system and the flow. Correlations between the morphological evolution along the extruder and the thermorheological properties of the composites are identified.
