Ref HAL: hal-01920652_v1
Exporter : BibTex | endNote
Résumé:

Small-angle scattering of neutrons (SANS) or x-rays (SAXS) are powerful experimental methods giving insight in the structure on the nanoscale of typical soft matter systems, like colloids or polymers, in solution or in bulk. In the first part of this lecture, the basic concepts of small angle scattering will be introduced and applied to the structural determination of popular nanostructures, like nanoparticle (NP) sizes, characterization of NP assemblies, including fractal aggregates, as well as polymer chain conformations. Usually, they are all investigated as single component in binary systems, like NPs suspended in a solvent. In the second part, a few examples in the field of polymer nanocomposites will be discussed, see ref. [1] for a review. The formation of aggregates may be tuned by different physico-chemical parameters, like those governing electrostatic interactions, surface modifications of NPs, or chain grafting, with direct consequences on the mechanical reinforcement of such materials [2]. In this context, both model nanocomposites [3] and samples close to industrial applications [4,5] like car tires will be studied. Chain configurations in complex systems like nanocomposites can be studied by SANS experiments. This requires the formulation of ternary systems made of deuterated and hydrogenated polymer, plus the filler NPs, and is possible using zero-average contrast conditions or similar [6]. Finally, a recently proposed model explaining the repeated (and expensive!) failures – including our own – will be discussed [7]. [1] Genix AC, Oberdisse J, Structure and dynamics of polymer nanocomposites studied by X-ray and neutron scattering techniques, Current Opinion in Colloid and Interface Science, 2015, 20 (4), 293-303.[2] Oberdisse J, Soft Matter 2006, 2 (1), 29-36.[3] Banc A, Genix AC, Chirat M et al. Tuning structure and rheology of silica-latex nanocomposites with the molecular weight of matrix chains: a coupled SAXS-TEM-simulation approach. Macromolecules 2014; 47:3219–3230.[4] Baeza GP, Genix AC, Degrandcourt C et al. Multiscale Filler Structure in Simplified Industrial Nanocomposite Silica/SBR Systems Studied by SAXS and TEM. Macromolecules 2013; 46:317-329[5] Baeza GP, Genix AC, Degrandcourt C et al. Mechanism of aggregate formation in simplified industrial silica styrene-butadiene nanocomposites: effect of chain mass and grafting on rheology and structure. Soft Matter 2014; 10:6686–6695.[6] Genix AC, Tatou M, Imaz A et al. Modeling of Intermediate Structures and Chain Conformation in Silica−Latex Nanocomposites Observed by SANS During Annealing. Macromolecules 2012; 45:1663–1675.[7] Banc A, Genix AC, Dupas C et al. On the origin of small-angle scattering from contrast-matched nanoparticles: A study of chain and filler structure in polymer nanocomposites. Macromolecules 2015; 2015, 48, 6596−6605.

Ref HAL: hal-01920623_v1
Exporter : BibTex | endNote
Résumé:

Small-angle scattering applied to microemulsions and liquid crystals

Ref HAL: hal-01920620_v1
Exporter : BibTex | endNote
Résumé:

Small-angle scattering applied to the sequence of morphologies of self-assembled structures

Ref HAL: hal-01919977_v1
DOI: 10.1122/1.4960333
WoS: 000384392300009
Exporter : BibTex | endNote
11 Citations

Ref HAL: hal-01876989_v1
Exporter : BibTex | endNote

Ref HAL: hal-01292652_v1
Ref Arxiv: 1603.06703
DOI: 10.1063/1.4972253
WoS: 000392096800036
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
10 Citations
Résumé:

We develop and thoroughly test a stress-controlled, parallel plates shear cell that can be coupled to an optical microscope or a small angle light scattering setup, for simultaneous investigation of the rheological properties and the microscopic structure of soft materials under an imposed shear stress. In order to minimize friction, the cell is based on an air bearing linear stage, the stress is applied through a contactless magnetic actuator, and the strain is measured through optical sensors. We discuss the contributions of inertia and of the small residual friction to the measured signal and demonstrate the performance of our device in both oscillating and step stress experiments on a variety of viscoelastic materials.

Ref HAL: hal-01292690_v1
Ref Arxiv: 1603.06384
DOI: 10.1016/j.optlaseng.2016.07.006
WoS: 000385319500002
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
16 Citations
Résumé:

We couple a laser-based, space-resolved dynamic light scattering apparatus to a universal testing machine for mechanical extensional tests. We perform simultaneous optical and mechanical measurements on polyether ether ketone, a semi-crystalline polymer widely used in the industry. Due to the high turbidity of the sample, light is multiply scattered by the sample and the diffusing wave spectroscopy (DWS) formalism is used to interpret the data. Space-resolved DWS yields spatial maps of the sample strain and of the microscopic dynamics. An excellent agreement is found between the strain maps thus obtained and those measured by a conventional stereo-correlation bench. The microscopic dynamics reveals both affine motion and plastic rearrangements. Thanks to the extreme sensitivity of DWS to displacements as small as 1 nm, plastic activity and its spatial localization can be detected at an early stage of the sample deformation, making the technique presented here a valuable complement to existing material characterization methods.