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Nanostructures & Spectroscopie
(85) Production(s) de l'année 2018
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Non-destructive DRIFT spectroscopy measurement of the degree of curing of industrial epoxy/silica composite buildup layers
Auteur(s): Granado Lérys, Maurin D., Kempa Stefan, Gregoriades Laurence, Brüning Frank, Fréty Nicole, Anglaret E., Bantignies J.-L.
(Article) Publié:
Polymer Testing, vol. 70 p.188 - 191 (2018)
Ref HAL: hal-01902659_v1
DOI: 10.1016/j.polymertesting.2018.07.007
WoS: 000445993600024
Exporter : BibTex | endNote
3 Citations
Résumé: The degree of curing of epoxy composites and coatings is one key parameter to control the reliability of manufacturing processes, particularly in printed circuit board (PCB) manufacturing where epoxy buildup composites are partially cured before processing. We show that the reaction of curing of an industrially relevant buildup composite (epoxy-phenol reinforced with silica fillers) can be monitored by diffuse reflectance infrared Fourier transform (DRIFT) in the near-infrared range. The accuracy of DRIFT measurements is confirmed by comparison with measurements in transmission mode on reference composite samples. DRIFT is demonstrated to offer an easy and reliable measurement of the epoxy degree of curing on PCB coupons.
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Nano-porous structures via self-assembly of amphiphilic triblock copolymers: influence of solvent and molecular weight
Auteur(s): Nehache Sabrina, Semsarilar M., In M., Dieudonne-George P., Lai Kee Him J., Bron P., Quemener D.
(Article) Publié:
Journal Of Polymer Science Part A: Polymer Chemistry, vol. 9 p.193-202 (2018)
Ref HAL: hal-01680368_v1
DOI: 10.1039/c7py01853c
WoS: 000418645100006
Exporter : BibTex | endNote
4 Citations
Résumé: Control of film structures made from a polystyrene-polystyrene sodium sulfonate-polystyrene (PS-PNaSS-PS) copolymer micellar solution is investigated in a THF/water mixture. Four different copolymers (varying molecular weights) are synthesised via RAFT (Reversible Addition Fragmentation chain Transfer) polymerisation. Depending on parameters such as copolymer molecular weight, solvent composition and copolymer concentration, the PS-PNaSS-PS triblock self-assembles into different morphologies in solution and dry state. The effect of each parameter is investigated using characterization techniques such as AFM, TEM, Cryo-TEM, SEM and SAXS. The morphologies obtained for PS-PNaSS-PS are found to be extremely sensitive when the water content of the micellar solution is low. Among the structures observed, a highly ordered nano-porous film is obtained using a PS10k-PNaSS6k-PS10k triblock copolymer solution containing 3.0 wt% of water. This micellar solution is used to prepare a porous membrane for filtration applications. Pure water filtration data suggest a pore size in the range of ultrafiltration, making these membranes attractive for applications in the food industry, for bacteria, virus and protein removal.
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Phase transitions in polymorphic materials probed using space-resolved diffusing wave spectroscopy
Auteur(s): Nagazi M. Y., Dieudonne-George P., Brambilla G., Meunier Gerard, Cipelletti L.
(Article) Publié:
Soft Matter, vol. 14 p.6439-6448 (2018)
Ref HAL: hal-01896690_v1
DOI: 10.1039/c8sm00911b
WoS: WOS:000442269000021
Exporter : BibTex | endNote
1 Citation
Résumé: We use space-resolved dynamic light scattering in the highly multiple scattering regime (Photon Correlation Imaging Diffusing Wave Spectroscopy, PCI-DWS) to investigate temperature-induced phase transitions in polymorphic materials. We study paraffin wax as a simple model system and chocolate, a prototypical example of fat-based products exhibiting complex, history-dependent phase transitions. We find that microscopic dynamics measured using PCI-DWS show remarkable, non-monotonic behavior upon heating: they transiently accelerate when crossing phase transition and slow down above the transition temperature. Sub-micron resolution measurements of the local drift of the sample surface reveal that the speed-up of the dynamics is due to the strain field induced by the change in density at transition temperature. The transition temperatures obtained from PCI-DWS are found to be in excellent agreement with those inferred from complementary differential scanning calorimetry and X-ray scattering experiments, thereby validating PCI-DWS as a new, powerful tool for the characterization of phase transitions in complex soft matter. Finally, we demonstrate the unique possibilities afforded by space-resolved DWS by investigating the spatially heterogeneous response of poorly manufactured or composite chocolate samples.
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Glass transition of soft colloids
Auteur(s): Philippe A. M., Truzzolillo D., Galvan-myoshi Julian, Dieudonne-George P., Trappe Veronique, Berthier L., Cipelletti L.
(Article) Publié:
Physical Review E, vol. 97 p.040601 (2018)
Texte intégral en Openaccess :
PMID 29758608
DOI: 10.1103/PhysRevE.97.040601
WoS: WOS:000429636700001
30 Citations
Résumé: We explore the glassy dynamics of soft colloids using microgels and charged particles interacting by steric and screened Coulomb interactions, respectively. In the supercooled regime, the structural relaxation time τα of both systems grows steeply with volume fraction, reminiscent of the behavior of colloidal hard spheres. Computer simulations confirm that the growth of τα on approaching the glass transition is independent of particle softness. By contrast, softness becomes relevant at very large packing fractions when the system falls out of equilibrium. In this nonequilibrium regime, τα depends surprisingly weakly on packing fraction, and time correlation functions exhibit a compressed exponential decay consistent with stress-driven relaxation. The transition to this novel regime coincides with the onset of an anomalous decrease in local order with increasing density typical of ultrasoft systems. We propose that these peculiar dynamics results from the combination of the nonequilibrium aging dynamics expected in the glassy state and the tendency of colloids interacting through soft potentials to refluidize at high packing fractions.
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Ultrasensitive Displacement Noise Measurement of Carbon Nanotube Mechanical Resonators
Auteur(s): De bonis S. l., Urgell C., Yang W., Samanta C., Noury A., Vergara-cruz J., Dong Q., Jin Y., Bachtold A.
(Article) Publié:
Nano Letters, vol. 18 p.5324-5328 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01884447_v1
DOI: 10.1021/acs.nanolett.8b02437
WoS: WOS:000441478300097
Exporter : BibTex | endNote
16 Citations
Résumé: Mechanical resonators based on a singlecarbon nanotube are exceptional sensors of mass and force.The force sensitivity in these ultralight resonators is oftenlimited by the noise in the detection of the vibrations. Here,we report on an ultrasensitive scheme based on a RLCresonator and a low-temperature amplifier to detect nanotubevibrations. We also show a new fabrication process ofelectromechanical nanotube resonators to reduce the separation between the suspended nanotube and the gate electrodedown to ∼150 nm. These advances in detection and fabrication allow us to reach 0.5pm/ Hz displacement sensitivity.Thermal vibrations cooled cryogenically at 300 mK are detected with a signal-to-noise ratio as high as 17 dB. We demonstrate4.3zN/ Hz force sensitivity, which is the best force sensitivity achieved thus far with a mechanical resonator. Our work is animportant step toward imaging individual nuclear spins and studying the coupling between mechanical vibrations and electronsin different quantum electron transport regimes.
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Kinetic regimes in the curing process of epoxy-phenol composites
Auteur(s): Granado Lérys, Kempa Stefan, Gregoriades Laurence, Brüning Frank, Genix A.-C., Fréty Nicole, Anglaret E.
(Article) Publié:
Thermochimica Acta, vol. 667 p.185 - 192 (2018)
Ref HAL: hal-01881804_v1
DOI: 10.1016/j.tca.2018.07.019
WoS: 000444663600024
Exporter : BibTex | endNote
9 Citations
Résumé: Despite an abundant literature on epoxy-amine systems, a complete description of the curing kinetics in epoxy-phenol composites was still lacking. In this study, the curing kinetics of an epoxy-phenol composite relevant to microelectronics industry is probed by isothermal and non-isothermal differential scanning calorimetry. An isoconversional analysis of the data reveals a significant contribution of the diffusion of molecular species to the activation energy, at low temperature and high degrees of curing. A model-fitting of the kinetics is performed in two successive steps: high-temperatures data are fitted with Arrhenius law and nth order autocatalytic model (where the diffusion contribution is neglected), whereas low-temperature data are fitted using Rabinowitch and modified-Williams-Landel-Ferry models (considering a diffusion contribution related to the glass transition). The chemical and diffusion contributions to the rate constants are calculated at various temperatures, clarifying the kinetics regimes with precision. Finally, the kinetics regimes are summarized in an improved time-temperature-transformation diagram.
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Carbon nanotubes functionalized with copper Hexacyanoferrate nanoparticles for a selective extraction of cesium from liquid waste
Auteur(s): Draouil H, Alvarez L., Causse Jérémy, Flaud V., Zaïbi M, Bantignies J.-L., Oueslati M, Cambedouzou J.
(Article) Publié:
Materials And Devices, vol. 3 #2 p.0407 (2018) (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01845473_v1
DOI: 10.23647/ca.md20180407
Exporter : BibTex | endNote
Résumé: Single-walled carbon nanotubes are functionalized with copper hexacyanoferrate nanoparticles for the liquid-solid extraction of cesium from liquid waste and contaminated water. The functionalization process is followed mainly by x-ray photoemission spectroscopy. Indeed, determining the chemical environment around carbon or nitrogen atoms allows to evidence the formation of covalent bounding. In addition, the signatures of iron and copper ions give information on the effective growth of hexacyanoferrate nanoparticles. Furthermore, the cesium sorption mechanism is investigated by comparing the peak intensities associated to the response of potassium and cesium ions. Finally, based on the liquid chromatography analyzes, the sorption of cesium with the functionalized carbon supports is studied. The main results of this work are the demonstration of both a good selectivity of cesium trapping and a high sorption capacity by hybrid single-walled carbon nanotubes.
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