SYNTHESIS OF HYPERBRANCHED, HYDROPHILIC FLUORINATED SURFACE GRAFTS

The synthesis of 60-1000 Angstrom thick films of fluorinated polymers on gold and silica substrates via amidation of layered, hyperbranched poly(acrylic acid) surface-graft films with a fluorinated octylamine i s described. These syntheses proceed either by formation and fluoramid ation of layers of poly(acrylic acid) or by stepwise formation of laye rs of a mixture of poly(acrylic acid) and a fluorinated poly(acrylamid e) on a carboxylic acid-containing self-assembled monolayer on gold or on aminopropylated silica. Depending on the chemistry used, these gra fts can be prepared so that they have fluorinated interiors and either hydrophobic or hydrophilic exteriors. Ellipsometric studies of these grafts on gold show that the thickness of the layers can be controlled on the basis of the number of PAA layers present and that fluorinatio n using a fluorinated octylamine roughly doubled layer thickness. Infr ared and X-ray photoelectron spectroscopy studies were used to charact erize these surfaces.