Chemical modification of fluorinated self-assembled monolayer surfaces by low energy reactive ion bombardment

Reactive collisions of low energy (<100-eV) mass-selected ions are used to chemically modify fluorinated self-assembled monolayer surfaces comprised of alkanethiolate chains CF3(CF2)11(CH2)2S-bound to Au. Typical experiments were done by using 1-nA/cm2 beams and submonolayer doses of reactant ions. Characterization of the modified surface was achieved by in situ chemical sputtering (60-eV Xe+·) and by independent high mass resolution time-of-flight-secondary ionization mass spectrometry (TOF-SIMS) (15-25-keV, Ga+) experiments. Treatment with Si35C14+· produced a surface from which Xe+· sputtering liberated CF2 35C1+ ions, which suggested Cl-for-F halogen exchange at the surface. Isotopic labeling studies that used Si35Cl2 37Cl2+·; and experiments with bromine-containing and iodine-containing projectiles, confirmed this reaction. High mass resolution TOF-SIMS spectra, as well as high spatial resolution images, provided further evidence as to the existence of halogen-exchanged species at the bombarded surface. Analogous Cl-for-F halogen substitution was observed in a model gas-phase reaction. The ion-surface reaction is suggested to proceed through an intermediate fluoronium ion in which the projectile is bonded to the target molecule. The most significant conclusion of the study is that selective chemical modification of monolayer surfaces can be achieved by using reactive ion beams, which lead to new covalent bonds at the surface and in the scattered ions

Fluorine Plasma Treatments of Polypropylene Films, 1 – Surface Characterization Part 2: cf. ref. 11

In this work, an experimental investigation of fluorine gas (F 2 ) plasma treatment of polypropylene (PP) film reveals the evolution of PP fluorination. Surface analysis of fluorinated PP surfaces describes a surface modification process that is initially quite rapid but slows sharply as the fluorination progresses. The fluorination reaction occurs more rapidly at the PP film surface and evidence of a treatment gradient is seen in the ESCA sampling depth of 10 nm. The increasingly fluorinated surface becomes less reactive to the plasma chemistry and develops a fully fluorinated, cross-linked surface layer that eventually extends the full ESCA sampling depth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65033/1/107_ftp.pd