| 1. |
- Ahvenniemi, Esko, et al.
(författare)
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Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"
- 2017
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 35:1
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Forskningsöversikt (refereegranskat)abstract
- Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency.
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| 2. |
- Jin, Hua, et al.
(författare)
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Ionically interacting nanoclay and nanofibrillated cellulose lead to tough bulk nanocomposites in compression by forced self-assembly
- 2013
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Ingår i: Journal of Materials Chemistry B. - : Royal Society of Chemistry (RSC). - 2050-750X .- 2050-7518. ; 1:6, s. 835-840
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Tidskriftsartikel (refereegranskat)abstract
- Several approaches have recently been shown for self-assembled biomimetic composite films, aiming at combinations of high toughness, strength, and stiffness. However, it remains challenging to achieve high toughness using simple processes especially for bulk materials. We demonstrate that ionically interacting cationic native nanofibrillated cellulose (C-NFC) and anionic nanoclay, i.e. montmorillonite (MTM), allow local self-assemblies by a simple centrifugation process to achieve 3D bulk materials. The composite with MTM/C-NFC of 63/37 w/w has a high compressive strain to failure of 37% with distinct plastic deformation behaviour, a high work to fracture of 23.1 MJ m(-3), and a relatively high compression strength of 76 MPa. Unlike the conventionally used sequential deposition methods to achieve well-defined layers for the oppositely charged units as limited to films, the present one-step method allows quick formation of bulk materials and leads to local self-assemblies, however, having a considerable amount of nanovoids and defects between them. We suggest that the nanovoids and defects promote the plastic deformation and toughness. Considering the simple preparation method and bio-based origin of NFC, we expect that the present tough bulk nanocomposites in compression have potential in applications for sustainable and environmentally friendly materials in construction and transportation.
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| 3. |
- Hoshian, Sasha, et al.
(författare)
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Amplified and Localized Photoswitching of TiO2 by Micro- and Nanostructuring
- 2015
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:28, s. 15593-15599
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Tidskriftsartikel (refereegranskat)abstract
- Fast photoswitching of wetting properties is important for the development of micro/nanofluidic systems and lab-on-a-chip devices. Here, we show how structuring the surface amplifies photoswitching properties. Atomic layer-deposited titanium dioxide (TiO2) has phototunable hydrophilic properties due to its surface chemistry, but microscale overhang pillars and additional nanoscale topography can override the chemistry and make the surface sup erhydrophobic. Three switching processes are achieved simply by controlling the UV exposure time: from (1) rolling superhydrophobic to sticky superhydrophobic (Cassie-Baxter to Wenzel), (2) sup erhydrophobic to hydrophilic, and (3) superhydrophobic to superhydrophilic after 1, 5, and 10 min of UV exposure, respectively. We report the fastest reversible switching to date: 1 min of UV exposure is enough to promote a rolling-to-sticky transition, and mild heating (30 min at 60 degrees C) is sufficient for recovery. This performance is caused by a combination of the photoswitching properties of TiO2, the micropillar overhang geometry, and surface nanostructuring. We demonstrate that the switching also can be performed locally by introducing microwriting under a water droplet.
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| 4. |
- Mertaniemi, Henrikki, et al.
(författare)
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Rebounding Droplet-Droplet Collisions on Superhydrophobic Surfaces: from the Phenomenon to Droplet Logic
- 2012
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Ingår i: Advanced Materials. - : Wiley-VCH Verlag Berlin. - 0935-9648 .- 1521-4095. ; 24:42, s. 5738-5743
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Tidskriftsartikel (refereegranskat)abstract
- When water droplets impact each other while traveling on a superhydrophobic surface, we demonstrate that they are able to rebound like billiard balls. We present elementary Boolean logic operations and a flip-flop memory based on these rebounding water droplet collisions. Furthermore, bouncing or coalescence can be easily controlled by process parameters. Thus by the controlled coalescence of reactive droplets, here using the quenching of fluorescent metal nanoclusters as a model reaction, we also demonstrate an elementary operation for programmable chemistry.
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| 5. |
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| 6. |
- Xu, Wenyang, et al.
(författare)
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Solid-state polymer adsorption for surface modification : The role of molecular weight
- 2022
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 605, s. 441-450
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: Solid-state polymer adsorption offers a distinct approach for surface modification. These ultrathin, so-called Guiselin layers can easily be obtained by placing a polymer melt in contact with an interface, followed by a removal of the non-adsorbed layer with a good solvent. While the mechanism of formation has been well established for Guiselin layers, their stability, crucial from the perspective of materials applications, is not. The stability is a trade-off in the entropic penalty between cooperative detachment of the number of segments directly adsorbed on the substrate and consecutively pinned monomers. Experiments: Experimental model systems of Guiselin layers of polystyrene (PS) on silicon wafers with native oxide layer on top were employed. The stability of the adsorbed layers was studied as a function of PS molecular weight and polydispersibility by various microscopic and spectroscopic tools as well as quasi-static contact angle measurements. Findings: Adsorbed layers from low molecular weight PS were disrupted with typical spinodal decomposition patterns whereas high molecular weight (>500 kDa) PS resulted in stable, continuous layers. Moreover, we show that Guiselin layers offer an enticing way to modify a surface, as demonstrated by adsorbed PS that imparts a hydrophobic character to initially hydrophilic silicon wafers.
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| 7. |
- Yu, Cunming, et al.
(författare)
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Nature–Inspired self–cleaning surfaces: Mechanisms, modelling, and manufacturing
- 2020
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Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 155, s. 48-65
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Tidskriftsartikel (refereegranskat)abstract
- Nature-inspired self-cleaning surfaces have attracted considerable attention from both fundamental research and practical applications. This review adopts a chemical-engineering point of view and focuses on mechanisms, modelling, and manufacturing (M3) of nature-inspired self-cleaning surfaces. We will introduce six nature-inspired self-cleaning mechanisms: The Lotus-effect, superhydrophobic-induced droplet jumping, superhydrophobic-induced unidirectional movement of water droplet, underwater-superoleophobic-based self-cleaning, slippery-based self-cleaning, and dry self-cleaning. These mechanisms of nature self-cleaning examples are popular and well-known as well as have been widely applied or exhibited potential applications in our daily life and industrial productions. The mathematical and numerical modelling of the identified self-cleaning mechanisms will be carefully introduced, which will contribute to the rational design and reproducible construction of these functional self-cleaning surfaces. Finally, we will discuss how these materials can be produced, with a focus on scalable manufacturing. We hope this review will strengthen the understanding on nature-inspired self-cleaning surfaces and stimulate interdisciplinary collaboration of material science, biology and engineering.
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