Travelet C.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
Travelet C.,Joseph Fourier University |
Hebraud P.,CNRS Institute of Genetics and of Molecular and Cellular Biology |
Perry C.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
And 6 more authors.
Macromolecules | Year: 2010
The structure of polyrotaxanes (PRs) based on α-cyclodextrins (α-CDs) threaded onto 22 kg mol-1 poly(ethylene oxide) (PEO) chains in concentrated solution (≈20% w/w) in dimethyl sulfoxide (DMSO) was studied by small-angle neutron scattering (SANS) measurements as a function of the temperature and the complexation degree N (i.e., the number of threaded α-CDs per PR which ranged from 7 up to 157). A multiblock copolymers behavior was revealed for PRs in DMSO. This multiblock behavior of PRs at 43 °C is due to the presence of two kinds of blocks which alternate along the PR. One block type is rigid and corresponds to α-CD rodlike tubes with a length Lrod≈7 nm. The other block type corresponds to flexible naked PEO segments. When the PR mixtures are cooled down to 21°C, they gelify slowly with time and form transparent physical gels. The gel structure is due to the multiblock copolymer behavior of PRs leading to the formation of regular bundles for which the characteristic sizes (L = 14 nm and R = 5.7 nm) are constant during the gelation process and are independent with N. These regular bundles contain naked PEO segment crystallites surrounded by α-CD rodlike tube aggregates at their extremities. Indeed, α-CD rodlike tubes, which are present in the initial state at 43 °C, act like a compatibilizer and thus lead to the nanoscale bundle sizes and thus to the transparency of the physical PR-based gels. Furthermore, we showed that the kinetics of the bundle formation is N-dependent. Indeed, at constant PR weight fraction in DMSO, the N value is a crucial parameter controlling the intrinsic flexibility of PRs (flexibility favored at low N values) and their prealignment (prealignment favored at high N values) and thus controlling the self-organization. © 2010 American Chemical Society.
Halary J.L.,ESPCI ParisTech |
Averous L.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
Borredon M.-E.,ENSIACET |
Bourbigot S.,French National Center for Scientific Research |
And 12 more authors.
Actualite Chimique | Year: 2010
The second half of the 20th century, sometimes called "the plastic age", knew a boom of polymer materials in all the sectors of industrial activity. Nowadays, although polymer production is continuously growing, all the developed countries are facing new challenges regarding the rarefaction of fossil resources and the sustainable development. Many research works performed in the institutions affiliated to the "Fédé ration Gay-Lussac" aim to contribute to this field by exploring some new aspects of polymer science. They include: unusual polymerization reactions, new types of tri-dimensional networks, valorization of natural polymers, biocomposites and nano-biocomposites, durability of polymeric products.
Rondin J.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
Bouquey M.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
Muller R.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
Serra C.A.,Laboratoire dIngenierie des Polymeres Pour les Hautes Technologies |
And 2 more authors.
Polymer Engineering and Science | Year: 2014
Polypropylene and ethylene-propylene-diene terpolymer (PP/EPDM) blends were melt compounded in a new mixing device, designed in our laboratory under the trademark of RMX®, which predominantly generates elongational flows. Dispersion of the EPDM minor phase in PP was carried out in both RMX® and in an internal mixer (Haake Rheomix 600) at equivalent specific mixing energies and the resultant morphologies obtained by SEM were analyzed and compared. A better dispersive mixing efficiency of the RMX® mixer, i.e., lower D n and Dv of the dispersed EPDM phase was observed. The impact of elongational flow was more pronounced for blends having a high viscosity ratio p, indicating an enhanced droplet break-up mechanism, which was attributed to the combination of high shear rates inside the mixing element and important elongational flows in the convergent/divergent zones. The morphology of the blends was correlated with their linear viscoelastic properties by using the Palierne model. Very good agreement was found for the PP/EPDM 80/20 blends but for higher EPDM content, the Palierne model failed to describe the rheological behavior, which was attributed to percolation of the minor phase with increasing the concentration. Higher elasticity at low frequencies was observed for blends processed in the RMX®, which was attributed to a higher generated interfacial area. POLYM. ENG. SCI., 54:1444-1457, 2014. © 2013 Society of Plastics Engineers © 2013 Society of Plastics Engineers.
Marcati A.,Ecole Polytechnique - Palaiseau |
Serra C.,Laboratoire dIngenierie des Polymeres pour les Hautes Technologies |
Bouquey M.,Laboratoire dIngenierie des Polymeres pour les Hautes Technologies |
Prat L.,Ecole Polytechnique - Palaiseau
Chemical Engineering and Technology | Year: 2010
This paper deals with solid-liquid operations in microchannels. Continuous operations on solids (modification of frequency, change of solvent, encapsulation) in order to handle polymer particles in microchannels are described in terms of the limits of operating conditions and their possible applications. A methodology to design and implement operations on polymer particles is presented here. It is applied for the generation of onion-like structures. A microdevice completely built with Plexiglas plates and fused silica capillaries is used. The device includes droplet generation, polymerization and microparticle flow manipulation. The particles manipulated are in the range of 70 to 200 microns with a very low index of polydispersity.This articles deals with a methodology to manipulate particles. It is expected to define a design of a microsystem to produce more complex polymer structures by adding operations (frequency regulation, solvent change, particles encapsulation) after polymerization of particles. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.