| 1. |
- Park, Sung-Joon, et al.
(author)
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Autonomous Interfacial Assembly of Polymer Nanofilms via Surfactant-Regulated Marangoni Instability
- 2023
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 23:11, s. 4822-4829
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Journal article (peer-reviewed)abstract
- Interfacialpolymerization (IP) provides a versatile platform forfabricating defect-free functional nanofilms for various applications,including molecular separation, energy, electronics, and biomedicalmaterials. Unfortunately, coupled with complex natural instabilityphenomena, the IP mechanism and key parameters underlying the structuralevolution of nanofilms, especially in the presence of surfactantsas an interface regulator, remain puzzling. Here, we interfaciallyassembled polymer nanofilm membranes at the free water-oilinterface in the presence of differently charged surfactants and comprehensivelycharacterized their structure and properties. Combined with computationalsimulations, an in situ visualization of interfacial film formationdiscovered the critical role of Marangoni instability induced by thesurfactants via various mechanisms in structurally regulating thenanofilms. Despite their different instability-triggering mechanisms,the delicate control of the surfactants enabled the fabrication ofdefect-free, ultra-permselective nanofilm membranes. Our study identifiescritical IP parameters that allow us to rationally design nanofilms,coatings, and membranes for target applications.
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| 2. |
- Kim, Byung-Hyun, et al.
(author)
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Indirect-to-Direct Band Gap Transition of Si Nanosheets : Effect of Biaxial Strain
- 2018
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:27, s. 15297-15303
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Journal article (peer-reviewed)abstract
- The effect of biaxial strain on the band structure of two-dimensional silicon nanosheets (Si NSs) with (111), (110), and (001) exposed surfaces was investigated by means of density functional theory calculations. For all the considered Si NSs, an indirect-to-direct band gap transition occurs as the lateral dimensions of Si NSs increase; that is, increasing lateral biaxial strain from compressive to tensile always enhances the direct band gap characteristics. Further analysis revealed the mechanism of the transition which is caused by preferential shifts of the conduction band edge at a specific k-point because of their bond characteristics. Our results explain a photoluminescence result of the (111) Si NSs [U. Kim et al., ACS Nano 2011,.5, 2176-2181] in terms of the plausible tensile strain imposed in the unoxidized inner layer by surface oxidation.
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