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Selfa??Assembled PMMA Porous Membranes Decorated with In Situ Synthesized ZnO Nanoparticles with UVa??Tunable Wettability
摘要： This study reports a simple approach to fabricate porous poly(methyl methacrylate) (PMMA) membranes homogeneously decorated with exposed zinc oxide (ZnO) nanoparticles (NPs). This fabrication method significantly overcomes the disadvantages of both conventional foaming processes and incorporation of inorganic NPs in polymeric matrices. In particular, the porous structure is simply self-assembled by slowly evaporating a suitable solvent. The ZnO NPs are in situ formed by a thermally activated conversion of the zinc acetate precursor, previously embedded in the polymeric matrix. Scanning and transmission electron microscopy investigations show the formation of the desired self-assembled highly porous structure and ZnO NPs with branched morphology, respectively. The wetting behavior of the membranes surface is studied as a function of the ZnO content and UV irradiation, exploiting the switchable wettability of ZnO. The obtained unexpected results are then tentatively rationalized taking into account the surface chemistry and the roughness that arises from both porous structure and the different NPs dimensions and content.
关键词： porous membranes,nanocomposites,tunable wettability,self-assembly,in situ synthesis
更新于2025-09-23 15:21:01
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In Situ Study of Sputtering Nanometer-Thick Gold Films onto 100 Nanometer-Thick Spiro-OMeTAD Films: Implications for Perovskite Solar Cells
摘要： The performance of many perovskite solar cells is closely related to the spiro-OMeTAD/gold interface since gold is used as top contacts, which renders the detailed understanding of the interface formation very important. In this work, sputter deposition as an industry-relevant, high-rate, large-scale and well-controllable deposition technique is used to prepare gold electrodes on top of a 100 nm thick spiro-OMeTAD film. In situ grazing incidence small angle X-ray scattering (GISAXS) is used to study the nanostructure-growth kinetics of the gold contact on top of the spiro-OMeTAD film during the sputter process. The results show that the gold grows in nanoscale clusters, which then coalesce into a complete yet still nanogranular layer forming the top contact with a thickness of 90 nm. Based on simulations of the 2D GISAXS patterns additional information about the shape of the nanosized gold cluster is gained at the different cluster growth stages. Furthermore, the diffusion of gold into the spiro-OMeTAD film occurs during the sputter process as verified with X-ray reflectivity. In a depth of 3.5 nm below the gold contact the gold doping level of the spiro-OMeTAD film is 6.3 % irrespective of the final gold contact thickness. Thus, the interface between the spiro-OMeTAD film and the Au contact is not sharp as commonly sketched as well as the contact is grainy, which will be both of importance for the performance of device such as perovskite solar cells.
关键词： gold contacts,spiro-OMeTAD film,sputter deposition,in situ GISAXS,growth kinetics
更新于2025-09-23 15:21:01
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Imaging Supramolecular Morphogenesis with Confocal Laser Scanning Microscopy at Elevated Temperatures
摘要： The morphogenesis of supramolecular assemblies is a highly dynamic process that has only recently been recognized, and our understanding of this phenomenon will require imaging techniques capable of crossing scales. Shape transformations depend both on the complex energy landscapes of supramolecular systems and the kinetically controlled pathways that define their structures and functions. We report here the use of confocal laser scanning microscopy coupled with a custom-designed variable-temperature sample stage that enables in situ observation of such shape changes. The submicrometer resolution of this technique allows for real-time observation of the nanostructures in the native liquid environments in which they transform with thermal energy. We use this technique to study the temperature-dependent morphogenic behavior of peptide amphiphile nanofibers and photocatalytic chromophore amphiphile nanoribbons. The variable-temperature confocal microscopy technique demonstrated in this work can sample a large volume and provides real-time information on thermally induced morphological changes in the solution.
关键词： in situ microscopy,confocal microscopy,nanofibers,nanoribbons,supramolecular assembly
更新于2025-09-23 15:21:01
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The coupled dynamics of colloidal nanoparticle spreading and self-assembly at a fluid-fluid interface
摘要： We investigated the physicochemical and transport phenomena governing the self-assembly of colloidal nanoparticles at the interface of two immiscible fluids. By combining in-situ grazing incidence small-angle X-ray scattering (GISAXS) with a temporal resolution of 200 ms and electron microscopy measurements we gained new insights into the coupled effects of solvent spreading, nanoparticle assembly and recession of the vapor-liquid interface on the morphology of the self-assembled thin films. We focus on oleate-passivated PbSe nanoparticles dispersed across an ethylene glycol subphase as a model system and demonstrate how solvent parameters such as surface tension, nanoparticle solubility, aromaticity and polarity influence the mesoscale morphology of the nanoparticle superlattice. We discovered that a nanoparticle precursor monolayer film spreads in front of the bulk solution and influences the fluid spreading across the subphase. Improved understanding of the impact of kinetic phenomena (i.e., solvent spreading and evaporation) on superlattice morphology is important to describe the formation mechanism and ultimately enable assembly of high-quality superlattices with long range order.
关键词： self-assembly,interfacial phenomena,in-situ GISAXS,nanoparticle superlattice,spreading dynamics
更新于2025-09-23 15:21:01
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Direct in situ TEM visualization and insight of the facet-dependent sintering behaviours of gold on TiO?
摘要： To prevent sintering of supported nanocatalysts is an important issue in nanocatalysis. A feasible way is to choose a suitable support. However, whether the metal-support interactions promote or prevent the sintering has not been fully identified due to the lack of confirmed evidences. Herein, we report on completely different sintering behaviours of Au nanoparticles on distinct anatase TiO2 surfaces by in situ TEM. The full in situ sintering processes of Au nanoparticles were visualized on TiO2 (101) surface, which coupled the Ostwald ripening and particle migration coalescence. In contrast, no sintering of Au on TiO2 anatase (001) surface was observed under the same conditions. This facet-dependent sintering mechanism is fully explained by the density function theory calculations. Our work not only offers the direct evidence of the important role of supports in the sintering process, but also provides insightful information for the design of sintering-resistant nanocatalysts.
关键词： in situ TEM,particle migration and coalescence (PMC),sintering,metal?support interaction (MSI),Au-TiO2,Ostwald ripening (OR)
更新于2025-09-23 15:21:01
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An all-solid-state lamellar-nanostructured polymer electrolyte in-situ-prepared from smectic liquid crystal for thermally stable dye-sensitized solar cells
摘要： A novel all-solid-state polymer electrolyte based on thiolate/disulfide redox couple was in-situ prepared from a lamellar-assembled liquid crystal precursor for dye-sensitized solar cells (DSSCs). The use of the thiolate/disulfide redox couple allowed the in-situ polymerization, which ensured both preservation of the lamellar nanostructure in electrolyte and sufficient interfacial contact in DSSC. Electrochemical analysis revealed that the lamellar-nanostructured electrolyte possessed charge transport ability and photovoltaic performance quite close to the liquid crystal electrolyte precursor. The resultant all-solid-state DSSCs showed a thermally stable photovoltaic performance with PCE higher than 2% from 35 to 90 °C. The method in using in-situ polymerization of nanostructured liquid crystals to prepare solid-state electrolytes shed a new light for efficient and stable all-solid-state DSSC preparation, especially in large-scale actual application.
关键词： All-solid-state polymer electrolyte,In-situ preparation,Smectic liquid crystal,Dye-sensitized solar cell
更新于2025-09-23 15:21:01
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New insights into the release mechanism of Cd2+ from CdTe quantum dots within single cells in situ
摘要： Cadmium-quantum dots (Cd-QDs) possess unique properties as optoelectronic devices for sensitive detection in food and biomedicine fields. However, the toxic effects of Cd-QDs to single cells is still controversial, due to the release mechanism of QDs to Cd2+ in situ and the cytotoxic effects of QDs and Cd2+ respectively are still unclear. In this paper, the release rule of Cd2+ from CdTe QDs within single cells was investigated in situ by using flow cytometry method and the dose-response relationships were explored. Besides, an all-inclusive microscopy system was optimized for live cell imaging to observe the real-time entry process of CdTe QDs into cells. We found that intracellular CdTe QDs and Cd2+ contents were increased based on the dosage and exposing time. A dissociated saturation of Cd2+ from CdTe QDs was exist within cells. CdTe QDs induced more serious cyto-toxicity on kidney cells than hepatocytes. The toxicity of oxidative stress, cell apoptosis effects induced by CdTe QDs and Cd2+ are also in consistent with this result. This research develops analytical method to quantify the uptake and release of Cd-QDs to primary cells in situ and can provide technical support in studying the cyto-toxicity portion contributed by nanoparticles (NPs) and metal ions.
关键词： Release mechanism,Aqueous phase QDs,Single cells,Cd,In situ
更新于2025-09-23 15:21:01
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Small fatigue crack growth behavior of Ti-6Al-4V produced via selective laser melting: In situ characterization of a 3D crack tip interactions with defects
摘要： Small fatigue crack growth (SFCG) behavior is examined for additively manufactured Ti-6Al-4V specimens with optimal and trial build conditions (representing an increased degree of defects) through a combination of in situ tomography and in situ energy dispersive X-ray diffraction. The results showed slower crack growth rates for the SFCG samples compared to the long cracks (which was not expected). In the case of the trial conditions, the increased levels of porosity deterred crack growth by blunting the crack, as evident by the in situ tomography characterization.
关键词： In situ tomography,Porosity,Energy dispersive X-ray diffraction,Process build conditions,Additive manufacturing
更新于2025-09-23 15:21:01
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Asphaltenes dissolution mechanism study by <i>in-situ</i> Raman characterization of a packed-bed microreactor with HZSM-5 aluminosilicates
摘要： Asphaltenes, the most aromatic component of heavy oil, are responsible for the fouling and impairment in flow lines, wellbores, and other production facilities in the petroleum industry. Aromatic solvents such as xylenes are commonly used for the asphaltenes’ cleaning process. Understanding the mechanism of asphaltenes’ dissolution in aromatic solvents is significant for the development of a remediation strategy. The reduction of a reactor’s characteristic length scale leads to the decrease in experimental period while providing high throughput information. Microfluidic systems with in-situ spectroscopy is an excellent platform for time-effective studies of the molecular behavior of asphaltenes in simulated sandstone reservoirs. Here, we injected the HZSM-5 zeolite nanoparticles (707 nm ·aggregate-1 in isopropanol solution) with varying Al2O3/SiO2 ratios (from 0 to 1/26) into the quartz porous media to represent reservoirs with different characteristic acidity. In-line UV-Vis spectroscopy enabled the direct measurement of the dissolution percentage, while in-situ Raman spectroscopy revealed where the dissolution took place within the porous media. In addition to bed occupancy, sheet sizes of asphaltenes molecules can also be determined by in-situ Raman spectroscopy. Our results show that the average sheet size of deposited asphaltenes molecules decreased from 2.97 ± 0.25 nm to 2.74 ± 0.26 nm after cleaning the porous media with xylenes. This trend is confirmed with the fluorescence emission spectra of dissolved asphaltenes molecules, where a 10-30 nm red-shift is present when referenced to asphaltenes source samples. These results provide an explanation to why the dissolution percentage of asphaltenes in aromatic solvents increases from 20.15 wt% to 51.00 wt% as the Al2O3 content increases. We can speculate that this increase in weight percentage is attributed to the differences in deposited asphaltenes molecules’ sheet size. These results reveal the importance of π-π interactions during asphaltenes dissolution process in the aromatic solvent. Our results provide the fundamental understanding of asphaltenes dissolution, which otherwise would be challenging to observe using any other analytical methods.
关键词： in situ Raman spectroscopy,Asphaltenes dissolution,Porous media
更新于2025-09-23 15:21:01
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<i>In Situ</i> Characterization of the Triphase Contact Line in a Brush-Coating Process: Toward the Enhanced Efficiency of Polymer Solar Cells
摘要： Solution processes have been widely used for making polymer ?lms in organic photoelectric devices but su?er from di?culties in controlling the ?lm formation. Here, by in situ characterization triphase contact lines (TCLs) in a brush-coating process, we clarify how TCLs a?ect the quality of as-prepared ?lms. By ?ne-tuning the dewetting of a binary polymer solution (P3HT:PCBM) via di?erent directions, TCLs with di?erent patterns lead to ?lms with di?erent morphologies. High-quality nanothin ?lms with larger crystallized sizes and higher orientations were enabled when TCLs were parallel to the brush edge, based on which the polymer solar cell shows higher power conversion e?ciency (2.665%) compared with that of the spin-coated ?lm.
关键词： in situ characterization,the Chinese brush,dewetting,triphase contact line,polymer ?lms
更新于2025-09-23 15:21:01