Langmuir-Blodgett

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Lipid reassembly in asymmetric Langmuir-Blodgett/Langmuir-Schaeffer bilayers

Lipid reassembly in asymmetric Langmuir-Blodgett/Langmuir-Schaeffer bilayers

glass and glass substrates by LangmuirBlodgett (LB)/Langmuir−Schaeffer (LS) using binary lipid mixtures, namely, 1,2- dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and ternary mixtures DOPC/DPPC/1,2-dioleoyl-sn-glycero-3-phospho- L -serine (DOPS), labeled with 0.2 mol % Texas Red 1,2-dihexadecanoyl-sn- glycero-3-phosphoethanolamine triethylammonium salt (TR-DHPE) dye. Phase segregations were characterized by TIRF imaging, and DPPC-enriched domain structures were also observed. Interestingly for ∼40% (n = 6) of the samples with binary mixtures in the LB leaflet and a single component in the LS leaflet, that is, (DOPC/DPPC) LB +DOPC LS , the contrast of the DPPC domains changed from the original dark (without dye) to bright (more TR dye partitioning) on TIRF images, returning to dark again. This contrast reverse was also correlated to AFM height images, where a DPPC−DPPC gel phase was spotted after the TIRF image contrast returned to dark. The rupture force mapping results measured on these binary mixture samples also confirmed unambiguously the formation of DPPC−DPPC gel domain components during the contrast change. The samples were tracked over 48 h to investigate the lipid molecule movements in both the DPPC domains and the DOPC fluid phase. The fl uorescence contrast changes from bright to dark in SLBs indicate that the movement of dye molecules was independent of the movement of lipid molecules. In addition, correlated multimodal imaging using AFM, force mapping, and fluorescence provides a novel route to uncover the reorganization of lipid molecules at the solid−liquid interface, suggesting that the dynamics of dye molecules is highly structure dependent.
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Study of Langmuir-Blodgett Films of Self-Assembled Diblock Copolymers

Study of Langmuir-Blodgett Films of Self-Assembled Diblock Copolymers

different phases: G – gaseous, L 1 – liquid expanded, L 2 – liquid condensed, S – solid. ........................................................................................................................ 11 Figure 1-5. a) Langmuir trough (KSV 3000). b) The chemical structure of a typical LB compatible molecule with an aliphatic tail and a carboxylic acid head. ....................... 13 Figure 1-6. Langmuir-Blodgett deposition of monolayers from the water surface to a solid substrate.. .............................................................................................................. 14 Figure 1-7. Two different types of Langmuir-Schaefer deposition. ............................ 15 Figure 1-8. The principle of attenuated total reflection.. ............................................. 18 Figure 1-9. Schematic of the uniaxial orientation in an ultrathin film measured by polarized ATR.. ............................................................................................................. 19 Figure 1-10. Schematic image of the main morphology types in LB monolayers of amphiphilic diblock copolymers ................................................................................... 22 Figure 1-11. (A) Langmuir compression isotherm of PS-P4VP(29%)/PDP at the air/water interface. (B) Model of order-order transition as a result of barrier compression. (C-H) AFM height images (5 x 5 μm 2 ) of Langmuir-Blodgett (LB, in C- H) and Langmuir-Schaefer (LS, in G) monolayer films transferred at the surface pressures (π) indicated. ................................................................................................. 23 Figure 1-12. Height profiles of AFM images (500 x 250 nm 2 ) of LB films transferred at 30 and 40 mN/m respectively.................................................................................... 25 Figure 2-1. Molecular structure of PS-P4VP and the small molecules
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Influence of oxidized lipids on palmitoyl-oleoyl-phosphatidylcholine organization, contribution of Langmuir monolayers and Langmuir–Blodgett films

Influence of oxidized lipids on palmitoyl-oleoyl-phosphatidylcholine organization, contribution of Langmuir monolayers and Langmuir–Blodgett films

In a previous work, we studied the natural oxidation by atmospheric oxygen of Langmuir Blodgett (LB) films made of two monounsaturated lipids, POPC and OPPC (1 oleoyl 2 palmitoyl phosphatidylcholine), using atomic force microscopy (AFM) ( Faye et al., 2013 ). AFM is a high resolution scanning probe surface analysis technique, based on the measurement of interaction forces between a fine tip and the sample surface, these forces depending on the tip sample distance. By scanning the surface it is possible to image it with lateral and perpendicular resolutions of 1 nm and 0.1 nm, respectively. To our knowledge, this powerful imaging technique has not been applied in the case of membrane systems including oxidized lipids, whereas it is perfectly adapted to the non damaging study of lipid planar monolayers and bilayers ( Garcia Manyès et al., 2007; Garcia Manyès and Sanz, 2010; Faye et al., 2013 ). Moreover, AFM presents an important advantage as compared to widespread fluorescence microscopy, since this high resolution and non intrusive technique does not require the presence of a fluorophore, which can induce itself lipid oxidation ( Ayuyan and Cohen, 2006 ).
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Langmuir and Langmuir-Blodgett films of odorant binding protein/amphiphile study for odorant biosensor

Langmuir and Langmuir-Blodgett films of odorant binding protein/amphiphile study for odorant biosensor

For understanding well formation of Langmuir and Langmuir-Blodgett films, first we have studied the properties of monolayer at air/water interface. For studying adsorption of protein to amphiphile monolayer at the air/water interface, surface pressure-time curves (referred to as π -t) were recorded with opened barrier, namely without compressing force. The characteristics of the monolayer on the surface were studied by measuring the changes in surface pressure upon compressing the monolayer at a given temperature, namely surface pressure-molecular area isotherm (referred to as π -A). The shape of the isotherm is characteristic of the molecules making up the film. The stability of the monolayer, which is an important parameter for the stability of the mixed LB films, can be demonstrated by molecular area ratio-time evolution isotherms at the target pressure (referred to as A/A 0 -t) or surface pressure-time evolution at a
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Organisation en deux dimensions de nanoparticules métalliques et de copolymères à blocs à l’aide de la technique Langmuir-Blodgett

Organisation en deux dimensions de nanoparticules métalliques et de copolymères à blocs à l’aide de la technique Langmuir-Blodgett

the fabrication of plasmonic devices for use in metal-enhanced spectroscopies and the nanoscale manipulation of light. Conclusions LangmuirBlodgett film transfer is a useful tool for the bottom-up assembly of various composite systems. In particular, it constitutes a convenient route to model systems for the study of ordered block copolymer/inorganic NP composites. With this technique, we have demonstrated that the surface micelle morphology of PS-b-PMMA can be exploited to pattern the assembly of thiol-capped gold NPs. The precise location of the NPs, as well as the nature of their assembly, depends on both particle size and nature of the capping ligand. By tailoring these parameters, NPs can be dispersed in the PS domains, segregated at the PS-PMMA interface or aggregated into larger island-like arrays. This behavior can be, in part, rationalized with entropic considerations. In the case of hard-sphere particles, observations are in qualitative agreement with predicted trends. Particles with longer ligands, relative to their core radii, tend to assemble in a less defined way. In this case, the ligand shell is less dense and the particles cannot be treated as hard spheres. Free volume in the shell allows for interpenetration with the matrix polymer chains, favoring NP dispersion. In the case of particle aggregation at the PS-PMMA interface, increased NP loading can provoke a morphological transition from surface micelles to nanostrands. Although the detailed organization of these complex multiparameter systems cannot yet be predicted with certainty, well-defined NP assemblies are obtained.
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Films Langmuir-Blodgett composés de copolymères di-blocs et de nanoparticules métalliques

Films Langmuir-Blodgett composés de copolymères di-blocs et de nanoparticules métalliques

Résumé Cette thèse de doctorat étudie l’auto-assemblage de copolymères di-blocs et de nanoparticules métalliques à l’interface air-eau. Les nanoparticules métalliques peuvent interagir fortement avec la lumière grâce à l’oscillation collective des électrons de conduction. Ce phénomène, qu’on appelle le plasmon de surface localisé, offre d’importantes perspectives dans l’élaboration de matériaux optiques. Cependant, la force et la fréquence du plasmon de surface varient significativement en fonction de plusieurs paramètres dont l’arrangement des nanoparticules. Les copolymères à blocs, quant à eux, ont la capacité de former des domaines de morphologies définies à la surface de l’eau et représentent une voie simple pour organiser les nanoparticules en deux dimensions. Avec la technique Langmuir-Blodgett, il a été possible de former des monocouches composites de nanoparticules et de copolymères, et de les transférer sur des substrats solides. Les films composites Langmuir-Blodgett ont été caractérisés par microscopie à force atomique et par microscopie électronique en transmission. Plusieurs auto-assemblages, incluant des agrégats, des systèmes cœur-satellites, des cercles et des lignes de nanoparticules ont été observés. Les caractéristiques structurales de ces assemblages peuvent être ajustées avec précision en modifiant l’organisation des copolymères et la longueur des ligands thioalcanes à la surface des nanoparticules. De plus, une procédure de recroissance in
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Multilayer Langmuir-Blodgett films as diffractive external 3D photonic crystal in blue OLEDs.

Multilayer Langmuir-Blodgett films as diffractive external 3D photonic crystal in blue OLEDs.

Patterning the inner layers of large area OLEDs for internal outcoupling is a challenge [16], and may also have incidence on the color of the final OLED [17]. Therefore, we choose to structure the outer surface of a bottom emitting OLED, for technological reasons [18–21]. In many cases, the outcoupling layers are made of microstructures such as microparticles [22], microlenses [23], micro and nano-voids assembled in a monolayer [24], or periodic structures deposited on top of the glass substrate [25]. However, some of these nanopatterned diffractive grating structures involve complex and expensive elaboration processes, far from the stringent requirements of ease of fabrication for OLEDs mass production. Some disordered extraction layers [24] are easier to fabricate, but their optical properties may be difficult to model, leading to tough engineering steps in order to optimize the yield of the device. Besides, it is unsure that their fabrication would be reproducible at large, industrial scale. The Langmuir-Blodgett (LB) technique, on the contrary, is a very attractive way of producing ultrathin films with a precise control of the thickness, pattern size and shape [26, 27]. Besides, recent results show that this technique can be scaled up, using a roll-to-roll method [28], to make films of large surface containing several layers of dielectric beads, that could be stick onto an OLED to improve its yield, and may even be compatible with flexible OLEDs. The spatial periodicity of the extraction film, and therefore, of the whole OLED, permits to model their optical properties accurately and rapidly. To do this, we have extended to three dimensions the incoherent reflection/transmission formalism which is typically used to simulate OLEDs as unidimensional [29-31] or two-dimensional [32] systems. In particular, our model decouples the influence of internal layers and external coating, and permits to evaluate rapidly the OLED efficiency for different internal architectures (e.g. different EML thicknesses or point source location), without redoing all the computations. This leads to a better understanding of the mechanisms at stake, and makes it possible to obtain quantitative predictions on the improvement of light extraction, in which the 3D optical but also the 1D electrical OLED architecture plays an important role.
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From Langmuir–Blodgett to Grafted Films

From Langmuir–Blodgett to Grafted Films

A locally organized monolayer film strongly attached to a gold surface is obtained by transfer of a Langmuir Blodgett (LB) film of octadecylamine (ODA) or alcohol (ODOH) onto an Au surface and simultaneous oxidative electrografting of this film still in contact with the aqueous subphase. As opposed to LB films, these films resist ultrasonication and unlike electrografted films, they are organized monolayers by construction. They are characterized by AFM (Atomic Force Microscopy), water contact angle, ellipsometry, XPS (X-ray photoelectron spectroscopy) IRRAS (Infrared Reflection Absorption Spectroscopy) and GIXD (Grazing Incidence X-ray Diffraction).
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Polymères amphiphiles : des films Langmuir-Blodgett au transistor

Polymères amphiphiles : des films Langmuir-Blodgett au transistor

Le premier objectif de ce projet est la synthèse de polymères amphiphiles. L’obtention de ces molécules permettra de préparer des films de Langmuir. L’amphiphilicité est nécessaire à l’interface air-eau pour avoir un contrôle optimal de l’orientation. La partie hydrophile des polymères sera dans la sous-phase pendant que la partie hydrophobe sera orientée dans l’air tout le long de la compression. Le choix de la chaîne hydrophile sera porté sur une chaîne d’oxyde d’éthylène (OE); les longueurs seront variables. Cette chaîne ne devrait pas être trop longue, car cela risquerait d’induire une modification de l’organisation lors du transfert sur le substrat. Un catalogue de chaînes alkyle sera parcouru pour parfaire ces synthèses et fournir divers modèles de polymères amphiphiles à tester. Plusieurs aspects furent ainsi investigués tels que l’effet de la ramification de la chaîne latérale sur le TPD, le choix du monomère hydrophile ainsi que le choix du copolymère hydrophobe. Pour terminer, la méthode de synthèse a été optimisée pour conduire à des polymères avec des unités régiorégulières. Pour nous, l’importance était d’arriver à produire des molécules qui seraient très bien organisées par la technique Langmuir-Blodgett et qui offriraient de très bonnes performances pour les transistors.
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Third-order nonlinear optical study on sublimated/Langmuir-Blodgett thin films of lanthanide porphyrin phthalocyanine dimer/heterodimer and symmetric trimer systems by time-resolved non-degenerate four-wave mixing

Third-order nonlinear optical study on sublimated/Langmuir-Blodgett thin films of lanthanide porphyrin phthalocyanine dimer/heterodimer and symmetric trimer systems by time-resolved non-degenerate four-wave mixing

In symmetric bis- phthalocyanine and tris-phfhalocyanine- porphyrin the predominant process, rather than being electron transfer, is excitadon migration which causes an ultrafast nonline[r]

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Picosecond Generation of Transient Charge Carriers in Langmuir-Blodgett Films of Semi-Amphiphilic Heterodimers

Picosecond Generation of Transient Charge Carriers in Langmuir-Blodgett Films of Semi-Amphiphilic Heterodimers

In previous work, we have shown that the electron transfer can efficiently occur in heterodimers formed by pairing in solution positively or negatively charged porphyrin[r]

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Nanopatterning and functionalization of phospholipid-based Langmuir-Blodgett and Langmuir-Schaefer films

Nanopatterning and functionalization of phospholipid-based Langmuir-Blodgett and Langmuir-Schaefer films

No pre-transition was detected for DSDPPC by DSC or turbidity. The Tm of DSDPPC is 2-4 ºC higher then that of DPPC. The absence of a pre-transition suggests a restriction in cooperative disordering due to the molecular assymmetry caused by the methyldisulfide group and its bulkiness. The main transition enthalpy (ΔH) of DSDPPC (41.9 kJ mol -1 ) was found to be larger than that of DPPC (31.0 kJ mol -1 ). The higher ΔH of DSDPPC compared to DPPC can be due to either a more ordered and/or stable liquid crystalline phase through intermolecular interactions, presumably through -SSCH3 groups, or a less stable lamellar gel phase due to the bulkier –SSCH3 group and assymetric chains. According to Langmuir isotherms of DSDPPC, the molecules occupy a larger area than DPPC throughout the compression suggesting that a more disordered lamellar gel phase is more probable. The enthalpy of the DPPC phase transition is well within the range of literature values. The enthalpy values for the main transition of DPPC vary depending on the vesicle preparation method that will result in unilamellar vesicles or multilamellar vesicles of various sizes. The ionic strength of the buffer in which the vesicles are prepared will also affect the enthalpy.
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Highly Ordered Langmuir-Blodgett Films based on Semi-Amphiphilic Phthalocyanines

Highly Ordered Langmuir-Blodgett Films based on Semi-Amphiphilic Phthalocyanines

Published on 01 January 1989. View Article Online / Journal Homepage / Table of Contents for this issue.. The compression isotherm of the semi-amphiphilic mono- layer on the CoSl sol[r]

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Etude des films de Langmuir d'oxyde de graphène, de liquides ioniques et des systèmes mixtes

Etude des films de Langmuir d'oxyde de graphène, de liquides ioniques et des systèmes mixtes

4.5 Réduction des films Pour réaliser des mesures de courant tunnel, il faut mettre en place une différence de potentiels entre la pointe et la surface de l’échantillon. Nous avons essayé d’utiliser cette différence de potentiels pour provoquer la réduction du film d’oxyde de graphène, en se servant de la surface d’oxyde de graphène comme électrode et de la pointe conductrice d’un AFM couplé à un Microscope à Effet Tunnel comme contre-électrode. La première question que nous nous sommes posée a été "Est-il possible de mesurer des courants tunnel sur un film d’oxyde de graphène ?". Notre premier échantillon a été un film d’oxyde de graphène déposé par spin coating sur dioxyde de silicium. Nous avons ensuite cherché à savoir quelle était la direction privilégiée de la conductivité. Les électrons circulent-ils entre les épaisseurs de feuillets ? Ou circulent-ils le long des feuillets, dans le plan horizontal ? Nous avons utilisé des échantillons réalisés en Langmuir Blodgett sur une surface d’or (donc conductrice), avant de travailler avec des films d’oxyde de graphène réalisés en
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Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase

Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase

New experiments on Langmuir monolayers of C 11 F 23 CO 2 H perfluorinated fatty acid enabled a more accurate determination of the Langmuir isotherm and characterization of the observed phases and their transitions. X-ray reflectivity and grazing incidence X-ray diffraction measurements performed on the transition plateau to the LC phase with a higher resolution instrument provided evidence for the existence of “2D smectic C phase” that was not previously detected. This new phase was believed to result from the relatively weak intermolecular interactions between the perfluorinated chains associated with their rigidity and large aspect ratio. Indeed, weak intermolecular interactions induced a relatively low critical temperature for the transition to the LC phase, increasing the reduced temperature at which the experiments are performed. This resulted in a small width of the coexistence plateau and thus a relatively high density of the coexisting fluid phase. At such high density, the average area per molecule was necessarily lower than occupied by molecules lying parallel to the surface. This led to a tilting of the chains, which were associated with their stiffness and large aspect ratio, resulting in an orientation and packing process, leading to the appearance of parallel lines, forming the 2D smectic C organization. Atomistic molecular dynamics simulations provided a molecular-level interpretation of the results and visualization of the studied system. Moreover, the diffraction spectrum calculated from the simulation results compared favorably with the experimental pattern, fully validating the simulations and the proposed interpretations. In conclusion, three phases G, F, and LC should be considered in the phase diagram of monolayers formed by rigid chain fluorinated molecules.
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Batch-microfabricated miniaturized planar arrays of Langmuir probes for reentry plasma diagnostics and nanosatellites

Batch-microfabricated miniaturized planar arrays of Langmuir probes for reentry plasma diagnostics and nanosatellites

The plasma parameters measured by the MEMS Langmuir probe were within the range of VTF's reported plasma parameters, but the estimates of the electron density and [r]

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Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak

Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak

ABSTRACT Langmuir probe diagnostic systems presently employed on Alcator C-Mod and elsewhere generally suffer from a severe limitation: unless multiple electrode or high-frequency bias techniques are employed, these systems can not resolve the rapid changes in plasma electron temperature, floating potential and ion saturation current that are associated with plasma turbulence. Moreover, no existing system can provide real-time output of these three parameters using a single electrode. To remedy this limitation, an advanced, high-bandwidth Langmuir probe system has been constructed for Alcator C-Mod using state-of-the-art design tools and components. The system produces a fast-switched, three-state probe bias waveform and employs a new method for outputting plasma conditions in real-time, a ‘Mirror Langmuir Probe’ (MLP), which utilizes high-bandwidth bipolar transistors to electrically simulate a Langmuir probe’s response. Detailed information on the design, construction and performance of this new diagnostic is described in this thesis, representing the first proof-of-principle demonstration of the MLP technique. The MLP system was found to meet all the performance goals set forth at the beginning of the project: real-time output of electron temperature, floating potential and ion saturation current, ability to track changes in plasma parameters within a ~1 μs timescale, while utilizing only a single Langmuir electrode. The system was tested using an ‘electronic Langmuir probe’ and also using an actual Langmuir probe in Alcator C-Mod. In both cases, the system accurately locked onto changing plasma conditions (< ~5% error in outputted parameters), with the exception of some severe transient events found in C-Mod plasmas (ELMs), which challenged the system’s accuracy. Further refinements to the system have been identified to handle such cases. The MLP clearly demonstrated superior performance to existing Langmuir probe systems on Alcator C-Mod and should enable researchers to study edge plasma turbulence in much greater detail in the future.
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Construction and Operation of a Mirror Langmuir Probe Diagnostic for the Alcator C-Mod Tokamak

Construction and Operation of a Mirror Langmuir Probe Diagnostic for the Alcator C-Mod Tokamak

ABSTRACT Langmuir probe diagnostic systems presently employed on Alcator C-Mod and elsewhere generally suffer from a severe limitation: unless multiple electrode or high-frequency bias techniques are employed, these systems can not resolve the rapid changes in plasma electron temperature, floating potential and ion saturation current that are associated with plasma turbulence. Moreover, no existing system can provide real-time output of these three parameters using a single electrode. To remedy this limitation, an advanced, high-bandwidth Langmuir probe system has been constructed for Alcator C-Mod using state-of-the-art design tools and components. The system produces a fast-switched, three-state probe bias waveform and employs a new method for outputting plasma conditions in real-time, a ‘Mirror Langmuir Probe’ (MLP), which utilizes high-bandwidth bipolar transistors to electrically simulate a Langmuir probe’s response. Detailed information on the design, construction and performance of this new diagnostic is described in this thesis, representing the first proof-of-principle demonstration of the MLP technique. The MLP system was found to meet all the performance goals set forth at the beginning of the project: real-time output of electron temperature, floating potential and ion saturation current, ability to track changes in plasma parameters within a ~1 μs timescale, while utilizing only a single Langmuir electrode. The system was tested using an ‘electronic Langmuir probe’ and also using an actual Langmuir probe in Alcator C-Mod. In both cases, the system accurately locked onto changing plasma conditions (< ~5% error in outputted parameters), with the exception of some severe transient events found in C-Mod plasmas (ELMs), which challenged the system’s accuracy. Further refinements to the system have been identified to handle such cases. The MLP clearly demonstrated superior performance to existing Langmuir probe systems on Alcator C-Mod and should enable researchers to study edge plasma turbulence in much greater detail in the future.
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Black Brant IIA, AA-II-37: cosmic ray, Langmuir probe and micrometeorite launch

Black Brant IIA, AA-II-37: cosmic ray, Langmuir probe and micrometeorite launch

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB. Report (Nati[r]

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Etude des films de Langmuir de copolymères PS-b-PAA et formation de nanostructures inorganiques par réduction des ions argent à leur voisinage.

Etude des films de Langmuir de copolymères PS-b-PAA et formation de nanostructures inorganiques par réduction des ions argent à leur voisinage.

Figure 4.1: Représentation schématique d’une cuve de Langmuir. A l’aide d’une microseringue, les molécules amphiphiles sont déposées goutte à goutte à la surface de la sous-phase par le biais d’un solvant d’étalement. La cuve et les barrières sont en Téflon (ou recouvertes d’une feuille de Téflon) qui est un revête- ment hydrophobe inerte et facile à nettoyer. Avant chaque utilisation, la cuve est rincée plusieurs fois avec de l’eau ultra-pure (Millipore, de résistivité supérieure à 18 MΩ) ainsi que la verre- rie utilisée. Ceci est nécessaire pour éviter la présence d’impuretés à l’interface et assurer une interprétation correcte des résultats car les molécules formant la monocouche étant peu nom- breuses, une faible quantité d’impuretés dans la sous-phase peut modifier de façon significative le comportement du film et sa tension de surface. Pour les mêmes raisons, les solutions aqueuses sont réalisées avec de l’eau ultra-pure. Pour contrôler l’absence d’impuretés à l’interface, on réa- lise systématiquement un cycle de compression-expansion sur la sous-phase avant le dépôt des molécules à l’interface afin de vérifier que la pression de surface ne varie pas et reste bien nulle. Selon le type d’expériences réalisées lors de cette thèse, certaines des caractéristiques de la cuve de Langmuir utilisée (sa dimension, le nombre de barrières mobiles) peuvent différer. En effet, les mesures de diffusion ou de réflectivité de rayons x ou de neutrons réalisées in situ à l’interface air-eau son extrêmement sensibles au moindre écart de planéité. Le contrôle de la géométrie de l’interface doit être très précis et pour cela nous utilisons des cuves de Langmuir assez larges afin que la surface éclairée par le faisceau incident se trouve assez loin des ménisques sur les bords de la cuve.
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