Fluorinated poly(isobornyl methacrylate–co–butyl acrylate) core–shell latex nanoparticles: Synthesis, morphology and wettability of films

A fluorinated acrylate monomer simultaneously containing one hydrophilic hydroxyl and one hydrophobic perfluoroalkyl group was synthesized, which was then utilized to copolymerize with isobornyl methacrylate and butyl acrylate to prepare core–shell-structured latex nanoparticles through two-step emulsion polymerization. In this synthesis process, no any organic solvents or fluorine-containing surfactants were added. The perfluoroalkyl moieties are in the shell layer and the fluorine contents in the whole system range from 0 to 12.83 wt%. A clear core–shell interface is observed by transmission electron microscopy. The dynamic light scatterings show that the average particle sizes are around 95 nm. After film-formation, the angle-resolved XPS demonstrates that the ratios of F/C and CF3/CF2 have a significant gradient growth from the inner bulk up to the film surface, indicating that the fluorinated groups have segregated to the topmost layer with the CF3 termini oriented upward, which is consistent with the AFM images that some pointed bumps appear on the surface and the number increases with the fluorine content. As a consequence, the enriched perfluoroalkyl moieties, especially the CF3 groups, result in that the film with small amount of fluorine in the polymer exhibits a very low surface tension and high water contact angle.