| 1. |
- Bergendal, Erik, et al.
(författare)
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3D texturing of the air-water interface by biomimetic self-assembly
- 2020
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Ingår i: Nanoscale Horizons. - : Royal Society of Chemistry. - 2055-6764 .- 2055-6756. ; 5:5, s. 839-846
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Tidskriftsartikel (refereegranskat)abstract
- A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air-water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air-water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air-water interface.
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| 2. |
- Bergendal, Erik, et al.
(författare)
-
3D texturing of the air–water interface by biomimetic self-assembly
- 2020
-
Ingår i: Nanoscale Horizons. - 2055-6764 .- 2055-6756. ; :5, s. 839-846
-
Tidskriftsartikel (refereegranskat)abstract
- A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air–water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air–water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air–water interface.
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| 3. |
- Betker, Marie, et al.
(författare)
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Sprayed Hybrid Cellulose Nanofibril-Silver Nanowire Transparent Electrodes for Organic Electronic Applications
- 2023
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 6:14, s. 13677-13688
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Tidskriftsartikel (refereegranskat)abstract
- In times of climate change and resource scarcity, researchers are aiming to find sustainable alternatives to synthetic polymers for the fabrication of biodegradable, eco-friendly, and, at the same time, high-performance materials. Nanocomposites have the ability to combine several favorable properties of different materials in a single device. Here, we evaluate the suitability of two kinds of inks containing silver nanowires for the fast, facile, and industrial-relevant fabrication of two different types of cellulose-based silver nanowire electrodes via layer-by-layer spray deposition only. The Type I electrode has a layered structure, which is composed of a network of silver nanowires sprayed on top of a cellulose nanofibrils layer, while the Type II electrode consists of a homogeneous mixture of silver nanowires and cellulose nanofibrils. A correlation between the surface structure, conductivity, and transparency of both types of electrodes is established. We use the Haacke figure of merit for transparent electrode materials to demonstrate the favorable influence of cellulose nanofibrils in the spray ink by identifying Type II as the electrode with the lowest sheet resistance (minimum 5 ± 0.04 Ω/sq), while at the same time having a lower surface roughness and shorter fabrication time than Type I. Finally, we prove the mechanical stability of the Type II electrode by bending tests and its long-time stability under ambient conditions. The results demonstrate that the mixed spray ink of silver nanowires and cellulose nanofibrils is perfectly suitable for the fast fabrication of highly conductive organic nanoelectronics on an industrial scale.
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| 4. |
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| 5. |
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| 6. |
- Brett, Calvin, et al.
(författare)
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Nanocellulose-Assisted Thermally Induced Growth of Silver Nanoparticles for Optical Applications
- 2021
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:23, s. 27696-27704
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Tidskriftsartikel (refereegranskat)abstract
- Optically responsive materials are present in everyday life, from screens to sensors. However, fabricating large-area, fossil-free materials for functional biocompatible applications is still a challenge today. Nanocelluloses from various sources, such as wood, can provide biocompatibility and are emerging candidates for templating organic optoelectronics. Silver (Ag) in its nanoscale form shows excellent optical properties. Herein, we combine both materials using thin-film large-area spray-coating to study the fabrication of optical response applications. We characterize the Ag nanoparticle formation by X-ray scattering and UV-vis spectroscopy in situ during growth on the nanocellulose template. The morphology and optical properties of the nanocellulose film are compared to the rigid reference surface SiO2. Our results clearly show the potential to tailor the energy band gap of the resulting hybrid material.
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| 7. |
- Brett, Calvin, et al.
(författare)
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Water-Induced Structural Rearrangements on the Nanoscale in Ultrathin Nanocellulose Films
- 2019
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 52:12, s. 4721-4728
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Tidskriftsartikel (refereegranskat)abstract
- Many nanoscale biopolymer building blocks with defect-free molecular structure and exceptional mechanical properties have the potential to surpass the performance of existing fossil-based materials with respect to barrier properties, load-bearing substrates for advanced functionalities, as well as light-weight construction. Comprehension and control of performance variations of macroscopic biopolymer materials caused by humidity-driven structural changes at the nanoscale are imperative and challenging. A long-lasting challenge is the interaction with water molecules causing reversible changes in the intrinsic molecular structures that adversely affects the macroscale performance. Using in situ advanced X-ray and neutron scattering techniques, we reveal the structural rearrangements at the nanoscale in ultrathin nanocellulose films with humidity variations. These reversible rearrangements are then correlated with wettability that can be tuned. The results and methodology have general implications not only on the performance of cellulose-based materials but also for hierarchical materials fabricated with other organic and inorganic moisture-sensitive building blocks.
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| 8. |
- Guo, Renjun, et al.
(författare)
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Degradation mechanisms of perovskite solar cells under vacuum and one atmosphere of nitrogen
- 2021
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Ingår i: Nature Energy. - : Springer Nature. - 2058-7546. ; 6:10, s. 977-
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Tidskriftsartikel (refereegranskat)abstract
- Extensive studies have focused on improving the operational stability of perovskite solar cells, but few have surveyed the fundamental degradation mechanisms. One aspect overlooked in earlier works is the effect of the atmosphere on device performance during operation. Here we investigate the degradation mechanisms of perovskite solar cells operated under vacuum and under a nitrogen atmosphere using synchrotron radiation-based operando grazing-incidence X-ray scattering methods. Unlike the observations described in previous reports, we find that light-induced phase segregation, lattice shrinkage and morphology deformation occur under vacuum. Under nitrogen, only lattice shrinkage appears during the operation of solar cells, resulting in better device stability. The different behaviour under nitrogen is attributed to a larger energy barrier for lattice distortion and phase segregation. Finally, we find that the migration of excessive PbI2 to the interface between the perovskite and the hole transport layer degrades the performance of devices under vacuum or under nitrogen. Understanding degradation mechanisms in perovskite solar cells is key to their development. Now, Guo et al. show a greater degradation of the perovskite structure and morphology for devices operated under vacuum than under nitrogen.
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| 9. |
- Harder, Constantin, et al.
(författare)
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Poly(sobrerol methacrylate) Colloidal Inks Sprayed onto Cellulose Nanofibril Thin Films for Anticounterfeiting Applications
- 2024
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 7:9, s. 10840-10851
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Tidskriftsartikel (refereegranskat)abstract
- The colloidal layer formation on porous materials is a crucial step for printing and applying functional coatings, which can be used to fabricate anticounterfeiting paper. The deposition of colloidal layers and subsequent thermal treatment allows for modifying the hydrophilicity of the surface of a material. In the present work, wood-based colloidal inks are applied by spray deposition on spray-deposited porous cellulose nanofibrils (CNF) films. The surface modification by thermal annealing of the fabricated colloid-cellulose hybrid thin films is investigated in terms of layering and hydrophobicity. The polymer colloids in the inks are core-shell nanoparticles with different sizes and glass transition temperatures (T-g), thus enabling different and low thermal treatment temperatures. The ratio between the core polymers, poly(sobrerol methacrylate) (PSobMA), and poly(-butyl methacrylate) (PBMA) determines the T-g and hence allows for tailoring of the T-g. The layer formation of the colloidal inks on the porous CNF layer depends on the imbibition properties of the CNF layer which is determined by their morphology. The water adhesion of the CNF layer decreases due to the deposition of the colloids and thermal treatment except for the colloids with a size smaller than the void size of the porous CNF film. In this case, the colloids are imbibed into the CNF layer when T-g of the colloids is reached and the polymer chains transit in a mobile phase. Tailored aggregate and nanoscale-embedded hybrid structures are achieved depending on the colloid properties. The imbibition of these colloids into the porous CNF films is verified with grazing incidence small-angle X-ray scattering. This study shows a route for tuning the nanoscale structure and macroscopic physicochemical properties useful for anticounterfeiting paper.
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| 10. |
- Jiang, Xinyu, et al.
(författare)
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Film Formation Kinetics of Polymer Donor and Nonfullerene Acceptor Active Layers During Printing Out of 1,2,4-Trimethylbenzene in Ambient Conditions
- 2023
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Slot-die coating is a promising upscaling fabrication method to promote commercialization in the field of organic solar cells. Herein, the nonfullerene active layer blend of a conjugated polymer PffBT4T-2OD and a small molecule acceptor EH-IDTBR, which is printed out of the nonhalogenated solvent 1,2,4-trimethylbenzene, is studied. The film formation kinetics of the active layer PffBT4T-2OD:EH-IDTBR is probed in terms of the temporal evolutions in morphology as well as molecular conformation and aggregation as revealed by in situ grazing-incidence small angle X-ray scattering and UV–vis spectroscopy during the film printing process. A five-regime mesoscale domain growth process is observed in the active layer from the liquid state to the final dry state. The solvent evaporation-induced domain growth is accompanied with molecular stacking in a distinct J-type aggregation of the acceptor and a slight H-type aggregation of the donor molecules. The printed active layers exhibit an edge-on dominated PffBT4T-2OD and a face-on dominated EH-IDTBR crystallite structure. Compared to the neat PffBT4T-2OD and EH-IDTBR films, in the active layer, the crystallite structure deviates slightly in lattice spacing.
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