Doctoral thesis viva voce: Mathieu Capelot

Step-growth Polymerization, Supramolecular Polymers and Vitrimers

Mathieu Capelot, doctorant - PhD Student Crédits : ESPCI ParisTechThe aim of this thesis was the design and synthesis of polymer materials that exhibit unusual combinations of properties. To this end, we used step-growth polymerization and simple and up-scalable chemical reactions.

First, we described chemically cross-linked networks that are permanent and insoluble, yet malleable, weldable and processable at high temperatures. To achieve this, we synthesized epoxy networks that can rearrange their topology by transesterification reactions without modification of the numbers of links. The versatility of the chemistry allows for an easy adjustment of the network structure, and thus the thermomechanical properties, by changing the monomers that are used. Catalysis brings control over the malleability properties. We called these networks "vitrimers" because, unlike almost all known organic and inorganic glass formers, their viscosity gradually decreases with temperature, in a very similar way to silica.

Then, using crystallizable moieties inspired by supramolecular chemistry, we obtained nanophase-segregated oligoamides. These materials exhibit mechanical properties similar to those of conventional thermoplastics, but with a remarkably lower melt viscosity. This feature permits to consider new applications for thermoplastics, that are generally formed of high molecular weight polymer chains.