LSS Group, Institut Laue-Langevin
71, ave des Martyrs
The lecture will present neutron scattering, with a focus on small angle neutron scattering (SANS) as a method to characterize soft matter systems such as polymers, gels, colloids, composites.
Neutrons are a very convenient tool for studying structure and dynamics of such systems, because of the large hydrogen content and the possibility of isotopic substitution with deuterium in soft matter, thus creating a large scattering contrast. The lecture will also discuss the complementarity between neutrons, X-rays and light as experimental probes.
The SANS-method will be illustrated with examples from polymer- and colloid science, using non-equilibrium (shear) and time-resolved scattering techniques.
“Neutron, X-rays and Light: Scattering Methods applied to Soft Condensed Matter”. Eds P. Lindner & T. Zemb, Elsevier – North Holland, Amsterdam (2002).
Department of Inorganic and Analytical Chemistry
University of Geneva, Sciences II, 30, Quai Ernest-Ansermet
1211 Geneva 4
Polyelectrolytes strongly influence colloidal stability or particle deposition processes, and this mechanism is highly relevant in waste water treatment, papermaking, and the development of advanced materials. In the last decades, a range of analytical techniques became available, which allow to probe the structure of adsorbed polyelectrolyte layers, their interaction forces, and particle aggregation rates. These techniques mainly include light scattering, reflectivity, quartz crystal microbalance, atomic force microscopy, and time-resolved light scattering. Based on these techniques, we were able to accumulate knowledge concerning the structure of adsorbed polyelectrolyte layers on oppositely charged surfaces and the resulting surface forces. Principal findings are that adsorbing polyelectrolyte lead to charge reversal and that the resulting layers are laterally heterogeneous and very thin (typically few nanometers). Interactions between these layers are principally controlled by electrostatic double-layer and van der Waals forces as described by the theory of Derjaguin, Landau, Verwey and Overbeek (DLVO). However, additional attractive non-DLVO forces are present, which are induced by lateral heterogeneities in the surface charge distribution (patch-charge attraction).
Université de Lyon
F-69003 Lyon, France
F-69621 Villeurbanne, France
CNRS, UMR 5223, Ingénierie des Matériaux Polymères, France
Over the last few years, the ionic liquids (ILs) have been of a large interest both for the academic and industrial fields because they have been widely promoted as a green solvent. Their unique properties, such as their chemical and thermal stability, low saturated vapor pressure, non-flammability, and good ionic conductivity make them as ideal candidates in a wide variety of applications in the chemical industry1. It is more recently that Ils were associated to polymers2. Indeed, they have been used mainly as polymerization media in several types of polymerization processes to prepare functional polymers or as solvent to solubilise some polymers like polysaccharides. ILs have also been investigated as components of polymeric matrices, as lubricants, plasticizers or as templates for porous polymers. Very used in the energy field, ILs have been considered as novel electrolytes in the batteries or fuel cells. In the manufacture of nanomaterials, ILs have also been efficient surfactants for different fillers such as lamellar silicates, carbon nanotubes or metal oxides. Recently, ILs were considered as functional building blocks to achieve high added value materials combining a nanoscale structuration with strongly enhanced physical properties3.
This short course will give a wide overview of the use of ILs in polymer science and will provide an opportunity to discuss interactions between Ils and polymer medium and the relationships structure-properties resulting from this combination.
1 Vidal L., Riekkola, M-J.; Canals, A. “Ionic Liquid-modified materials for solid-phase extraction and separation : a review” Analytica Chimica Acta (2012) 715, 19-41.
2 Lu, J.; Yan, F.; Texter, J. “Advanced applications of ionic liquids in polymer science” Progress in polymer science (2009) 34, 431-448.
3 Livi, S.; Gérard, J.F.; Duchet-Rumeau, J. « Ionic Liquids: structuration agents in a fluorinated matrix” Chemical Communications, (2011) 47, 3589-3591.
Dr. Ir. J. Duvigneau
Universiteit Twente / Aerotech Development
Carré 4251, Drienerlolaan 5
7522 NB Enschede
Tel: 053 4893322
Nanocomposite materials consisting of well dispersed inorganic nanofillers in a polymer matrix have often unique properties that are mainly ascribed to their large interface between the nanoparticles and the polymer matrix. In order to benefit to the largest extend of this interface dominated properties, obtaining well dispersed systems is necessary. To have well dispersed nanofillers it is of great importance to have control over the particle size, surface chemistry and the polymer composition. This will be demonstrated by discussing for example the dispersion states of clay nanoparticles in polymers and how this can be improved by tailoring the surface of the clay platelets. Especially with the continuously increasing number of nanoparticles that are tailor made their separation and characterization is of unambiguous importance. During the short course techniques such as centrifugation, dialysis, ultrafiltration, multiphase systems for the size, shape and surface chemistry dependent separation of nanoparticles will be discussed. Characterization of the prepared and purified nanoparticles by TEM, SEM and light scattering techniques will be covered. In the second part of the short course preparation and characterization of polymer nanocomposites will be covered. The dispersion of nanoparticles in polymers is often characterized by x-ray scattering techniques, electron microscopy and atomic force microscopy. Sample preparation approaches will be covered as well. In the last part of the course I will discuss the characterization of nanocomposites focusing on bulk properties of functional materials, e.g. mechanical, fire retardant and barrier properties. In summary this short course provides you with a broad overview of commonly used techniques to prepare and characterize nanoparticles and nanocomposites with emphasis on the quality of dispersion and improved functional materials.
Matière Molle et Chimie, ESPCI ParisTech
10 rue Vauquelin
75005 Paris France
Polymer rheology is extremely sensitive to macromolecular architectures and, as such, constitutes a very successful tool to investigate the structure and dynamics of polymeric materials. For a long time, the relationship between linear and non linear viscoelastic properties and polymer structures has been investigated using conventional rheological experiments. Theoretical methods have been developed to model synthetic polymers and commercial polymers.
However, it is often observed that large deformations result in various types of spatial heterogeneities which adversely affect the characterization and the processing of polymeric materials. A non exhaustive list of phenomena includes elastic instabilities, wall slip, melt fracture, and shear banding. Macroscopic experiments alone do not provide a complete picture of the physics at work.
These limitations have prompted the development of techniques which probe at the same time the bulk macroscopic rheology, the local structure and and the velocity and deformation fields during flow. We will review some very recent methods which have allowed significant achievements in the field: Large Amplitude Oscillatory Shear coupled to neutron and X rays scattering, direct visualization or simulations, Particle Image Velocimetry and Particle Tracking Velocimetry implemented in commercial rheometers and microfluidic devices.