Controlled Modification of Polymer Surfaces through Grafting of Calix[4]arene-Tetradiazoate Salts

Abstract

International audienceAn attractive methodology based on diazonium chemistry has been developed for the surface modification of polymers such as polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS). The grafting procedure involves the in situ formation of diazoates in basic aqueous solution. The reactivity of calix[4]arene-tetradiazonium salts and a classical aryldiazonium salt was examined through comparative studies on gold and polymer surfaces. The surfaces were analyzed with a combination of techniques such as AFM, XPS, and ellipsometry. The results highlighted the fact that the calix[4]arene molecules are grafted as a robust and uniform monolayer both on gold and polymer surfaces, allowing a fine control over surface modification. Furthermore, the chemical postfunctionalization of the grafted calixarene platforms equipped with carboxylic-pendant groups was successfully performed with either an amine or an alcohol. These results open real possibilities in the controlled immobilization on polymers of a wide variety of molecules of interest such as biomolecules or chromophores and in the tailoring of polymer properties

Synthesis of a Calix[4]arene‐Monodiazonium Salt for Surface Modification

“…Besides, when R contains a functional group such as COOH, a post‐functionalization of the surface can be readily achieved under mild conditions. Calix[4]arene‐tetradiazonium salts were notably used for the modification and further post‐functionalization of gold, carbon and germanium surfaces,, but also polymers and nanomaterials such as gold nanoparticles . Furthermore, this method allows for controlling the composition of binary mixed monolayers, which is essential for sensing applications , .…”

“…Surface modification with calix[4]arene‐tetradiazonium salts X 4 N 4 a – c , . Inset: targeted calix[4]arene‐monodiazonium salt 1 .…”

“…Indeed, such a calix [4]arene-monodiazonium salt would allow us to evaluate the influence of the number of anchoring points on the robustness and compactness of the grafted layer. Moreover, the number of anchoring points may also influence the 3D conformation of the calixarene once anchored onto the sur- [4]arene-tetradiazonium salts X 4 N 4 a-c. [7,[9][10][11][12][13] Inset: targeted calix [4]arene-monodiazonium salt 1. Note that the representation of the grafted calixarene does not necessarily imply that the four aryl units are linked to the surface.…”

Robust hydrophobic gold, glass and polypropylene surfaces obtained through a nanometric covalently bound organic layer

“…1). 4,[40][41][42][43][44][45][46][47] Calix [4]arenes are macrocycles composed of four phenolic units that are parasubstituted and linked in the ortho position through methylene bridges. These methylene bridges prevent polymerization of the diazonium derivatives, and hence lead solely to formation of monolayers.…”

“…This efficient surface modication strategy was already used on nanoparticles, 46,47 conductive, [41][42][43][44] semiconductive 4 and insulating surfaces. 45 Importantly, the use of calix [4]arenes allows to pre-organize four reactive functions in the same direction that could yield up to four covalent bonds with the surface, and hence potentially increase the monolayer's stability. Additionally, the calix [4]arene motif can be functionalized with up to four different substituents, which yields a molecular platform that can easily be post-functionalized through standard chemical transformations such as peptide coupling or click chemistry.…”