ESPCI web site
Damien Montarnal (CP2M-UMR 5128, University of Lyon)
Thursday the 9th of December, 11am - amphi Holweck
Recent developments and future challenges in vitrimer materials
Abstract :
Vitrimers aim at combining the benefits of thermoplastics and thermosets by incorporating in polymer networks dynamic covalent crosslinks governed by associative, exchangeable reactions in chemical equilibrium.[1] At high temperatures or in the presence of catalysts, chemical equilibria are fast enough to enable large scale reorganisation and stress relaxation of the network, and as a consequence plastic deformation, reprocessing and welding of the sample. In contrast with dissociative reversible networks that depolymerize at high temperatures, associative vitrimer networks remain crosslinked at all times and display a high melt elasticity and therefore a large adaptability to mould-free (re)processing techniques.
This very versatile concept has been successfully applied to different polymer systems by taking advantage of a variety of equilibrated reactions, either textbook or purposely developed.[2,3] Most vitrimers share however a common technological bottleneck : no satisfactory compromise has yet been found between fast (re)processing at high temperatures and very slow dynamics at service temperature guarantying creep resistance of the materials.
We will discuss in this scope the main features of dissociative and associative dynamic networks, and their respective linear rheological behaviors.[3] We will address some of our recent efforts to go beyond the weak temperature dependence of the exchange dynamics, presenting in particular “deactivable silicone vitrimers”.
Additionally to these developments on dynamic networks, we will present the synthesis of new functional porous materials that enable transportable Dynamic Nuclear Polarisation,[4] a recent NMR technique with revolutionary perspectives in both in-vitro and in-vivo detection of chemical transformations (reactional intermediates, metabonomics,…).