New alkylated and perfluoroalkylated phosphonic acids: Synthesis, adhesive and water-repellent properties on aluminum substrates

This paper describes the synthesis of phosphonic acids (R–S–(CH2)2–PO(OH)2) containing a perfluoroalkylated chain (R = C6F13–(CH2)2, C8F17–(CH2)2) or an alkyl group (R = C12H25, C18H37). These compounds, obtained in excellent yield by telomerization of vinyl phosphonic acid in the presence of alkylated or perfluorinated mercaptans used as transfer agents, were characterized by 1H, 19F and 31P nuclear magnetic resonance. Thermal characterization by differential scanning calorimetry (DSC) showed the presence of mesophases for compounds containing C8F17 and C18H37 end groups. A lamellar structure with a layered or bilayered organization was identified by small angle X-ray scattering (SAXS). Adhesion of these compounds on aluminum surfaces is improved by the presence of phosphonic groups. Hydrophobic properties of coated aluminum surfaces are enhanced by fluorinated groups.