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Alexis Chennevière received the 2015 Best PhD Award of the Société Française de Neutronique

The Société Française de Neutronique awarded the 2015 Best PhD prize to Alexis Chennevière for his thesis "Dynamics of graft polymer chains and sliding interfaces" performed at the Laboratoire de physique des solides under the direction of Liliane Léger and Frederic Restagno in the Team "Adhesion, friction and polymers."

In this thesis, several original results were obtained using neutron reflectivity experiments performed at Laboratoire Léon Brillouin in collaboration with François Boué and Fabrice Cousin.

In this thesis, the dynamics of a layer of polymer chains having one end covalently attached to a solid substrate was investigated. In a first part, the kinetics of healing of an interface between grafted chains on a substrate in contact with a melt was measured and modeled. The second part of the thesis consisted in the development of an experimental experimental setup for shearing a brush / molten system above the glass transition temperature and to freeze the conformation of the grafted chains into their sheared configuration. The inversion of the neutron reflectivity spectra allowed to demonstrate the influence of shear on the degree of interpenetration between the brush and the melt. This change in interpenetration governs the stress transmission on this type of interface. Finally, the relaxation kinetics of grafted chains into a film of thickness comparable to the chains radius of gyration revealed an acceleration of the relaxation kinetics. This could be interpreted in terms of a shift of the glass transition temperature as observed by other techniques.

Contact :

Frederic Restagno