| 1. |
- Liu, Jinrong, 1995-, et al.
(författare)
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Photonic crystals with rainbow colors by centrifugation-assisted assembly of colloidal lignin nanoparticles
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Photonic crystals are optical materials that are often fabricated by assembly of particles into periodically arranged structures. However, assembly of lignin nanoparticles has been limited due to lacking methods and incomplete understanding of the interparticle forces and packing mechanisms. Here we show a centrifugation-assisted fabrication of photonic crystals with rainbow structural colors emitted from the structure covering the entire visible spectrum. Our results show that centrifugation is crucial for the formation of lignin photonic crystals, because assembly of lignin nanoparticles without centrifugation assistance leads to the formation of stripe patterns rather than photonic crystals. We further prove that the functions of centrifugation are to classify lignin nanoparticles according to their particle size and produce monodispersed particle layers that display gradient colors from red to violet. The different layers of lignin nanoparticles were assembled in a way that created semi-closed packing structures, which gave rise to coherent scattering. The diameter of the lignin nanoparticles in each color layer is smaller than that predicted by a modified Bragg’s equation. In situ optical microscope images provided additional evidence on the importance of dynamic rearrangement of lignin nanoparticles during their assembly into semi-closed packing structures. The preparation of lignin nanoparticles combined with the methodology for their classification and assembly pave the way for sustainable photonic crystals.
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| 2. |
- Nero, Mathias, 1970-, et al.
(författare)
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The Nanoscale Ordering of Cellulose in a Hierarchically Structured Hybrid Material Revealed Using Scanning Electron Diffraction
- 2023
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Ingår i: Small Methods. - : Wiley. - 2366-9608.
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose, being a renewable and abundant biopolymer, has garnered significant attention for its unique properties and potential applications in hybrid materials. Understanding the hierarchical arrangement of cellulose nanofibers is crucial for developing cellulose-based materials with enhanced mechanical properties. In this study, the use of Scanning Electron Diffraction (SED) is presented to map the nanoscale orientation of cellulose fibers in a bio-composite material with a preserved wood cell structure. The SED data provides detailed insights into the ordering of cellulose with an extraordinary resolution of approximate to 15 nm. It enables a quantitative analysis of the fiber orientation over regions as large as entire cells. A highly organized arrangement of cellulose fibers within the secondary cell wall is observed, with a gradient of orientations toward the outer part of the wall. The in-plane fiber rotation is quantified, revealing a uniform orientation close to the middle lamella. Transversely sectioned material exhibits similar trends, suggesting a layered cell wall structure. Based on the SED data, a 3D model depicting the complex helical alignment of fibers throughout the cell wall is constructed. This study demonstrates the unique opportunities SED provides for characterizing the nanoscale hierarchical arrangement of cellulose nanofibers, empowering further research on a range of hybrid materials. Fundamental knowledge about the hierarchical arrangement of cellulose nanofiber is of great importance in developing new cellulose-based hybrid materials. Scanning electron diffraction is employed to map the cellulose nanofiber orientations throughout a wood-derived bio-based material. SED data reveals insights into cellulose alignment and enables precise quantitative fiber orientation analysis with a nanoscale spatial resolution.image
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| 3. |
- Samanta, Pratick, et al.
(författare)
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Coloration and Fire Retardancy of Transparent Wood Composites by Metal Ions
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:50, s. 58850-58860
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Tidskriftsartikel (refereegranskat)abstract
- Transparent wood composites (TWs) offer the possibility of unique coloration effects. A colored transparent wood composite (C-TW) with enhanced fire retardancy was impregnated by metal ion solutions, followed by methyl methacrylate (MMA) impregnation and polymerization. Bleached birch wood with a preserved hierarchical structure acted as a host for metal ions. Cobalt, nickel, copper, and iron metal salts were used. The location and distribution of metal ions in C-TW as well as the mechanical performance, optical properties, and fire retardancy were investigated. The C-TW coloration is tunable by controlling the metal ion species and concentration. The metal ions reduced heat release rates and limited the production of smoke during forced combustion tests. The potential for scaled-up production was verified by fabricating samples with a dimension of 180 x 100 x 1 (l x b x h) mm(3).
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