Tailored covalent grafting of hexafluoropropylene oxide oligomers onto silica nanoparticles: toward thermally stable, hydrophobic, and oleophobic nanocomposites.

The modification of silica nanoparticles with hexafluoropropylene oxide (HFPO) oligomers has been investigated. HFPO oligomers with two different average degrees of polymerization (DPn = 8 and 15) were first prepared by anionic ring-opening polymerization, deactivated by methanol, and in some cases postfunctionalized by aminopropyl(tri)ethoxysilane or allylamine. The "grafting onto" reactions of these oligomers were then carried out either on bare silica (reaction between a silanol surface and ethoxy-silanized HFPO) or on silica functionalized by amino groups (in an amidation reaction with methyl ester-ended HFPO) or mercapto groups (via the radical addition of allyl-functionalized HFPO).