Surface coating with ultrathin layers (monolayers) exhibiting a highly robust interface is of paramount importance for the design of materials with tailored properties. Currently, various chemical and physical coating methods can be used to modify a surface, but none of them allows the formation of a robust monolayer on various surfaces.

The X4C technology is a general surface modification methodology that can be applied to any conducting, semi-conducting or insulating surface. It involves the grafting of a calix[4]arene monolayer through the electrochemical or chemical reduction of the corresponding diazonium salt. This robust and controlled monolayer can be further post-modified by a large variety of molecules, biomolecules or nanoparticles to bring new properties to the surface.

The X4C technology was developed during the thesis of A. Mattiuzzi (CEO of X4C) in the Laboratory of Prof. I. Jabin (CSO of X4C) (Laboratory of Organic Chemistry, ULB). This research was developped in collaboration with Dr. C. Lagrost, Dr. P. Hapiot (Rennes 1 University) and Prof. O. Reinaud (Paris-Descartes University). The X4C technology was first developed onto gold and carbon surfaces and was then extended to various surfaces and nanoparticles. The technology was patented in 2012. After that, I. Jabin and A. Mattiuzzi obtained a public grant "FIRST Spin-Off” (2012-2015) for the creation of the X4C company in the Walloon Region.