Best presentation award for Lorenzo Casimiro

Lorenzo Casimiro, post-doctoral fellow within the
E-POM group received the prize for best presentation during the young researchers’ day. of the UFR of chemistry which took place on November 23.

Find the article on the UFR of chemistry newsletter

The butterfly effect of coordination polymers based on polyoxometalates

A challenge in the development of self-assembled nanomaterials is the insertion of switchable motifs that can both provide new properties and allow their control.

My activity within the IPCM (E-POM group, iSiM project coordinated by Guillaume Izzet), focuses on the preparation of supramolecular polymers by directed coordination of ditopic hybrids based on polyoxometallates (redox-active polyanionic oxo-clusters).

Through small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), TEM, polarized optical microscopy and rheometry measurements, we determined that, following complexation, the polymer chains self-assemble by electrostatic interaction into fibers, which, in turn, physically cross-link and lead to the formation of a gel.

On a macroscopic scale, these gels have remarkable viscoelastic properties, particularly in terms of self-repair after rupture. In addition, mechanical or thermal stimuli can induce self-alignment of the fibers giving the gel strong birefringence. Complexation therefore leads to a “butterfly effect” at the macroscopic level through a cascade of self-assembly reactions, which gives this soft material controllable properties by playing on the interactions involved and thanks to the switchable nature of the different units.