POMs are tridimensional ionic structures containing metallic atoms, such as tungsten or molybdenum, bound by oxygen atoms. They attract researchers' interest due to their many remarkable properties (catalytic, optical, magnetic, biological, etc.).

A team of chemists from ICSM has studied the interactions between a POM, phosphotungstate (PW) with α-Keggin structure and oligomers of ethylene oxide (EO). Using solutions of PW and EO, they managed to form a crystalline hybrid with oligomers of polyethylene glycol (PEG) in an aqueous environment and at room temperature.

To achieve this feat, the scientists had to understand and master the mechanisms at work. In aqueous solution, PW spontaneously associates with PEG. To trigger the formation of hybrid crystals from these self-assemblies, they had to mitigate the electrostatic repulsion between PW through the addition of salt (NaCl). From chemical species that were dispersed in solution, they eventually obtained a crystal whose pattern is an assembled set of PW (mineral) and PEG (organic).

The icing on the cake is that this study opens the way to a separation process for PEG oligomers according to their length.