Trifluoromethylation Of Carbonyl Groups In Aromatic Poly(Ether Ketone)S: Formation Of Strongly Polar Yet Surface-Hydrophobic Poly(Arylenenecarbinol)S

Fluoride-catalyzed reactions of trimethyl(trifluoromethyl)silane with a range of aromatic poly(ether ketone)s, both amorphous and semicrystalline, proceed quantitatively in THF to yield soluble, amorphous polymers in which the carbon-silicon bond of CF3SiMe3 has added across the carbonyl-oxygen double bond of each carbonyl group. When the starting poly(ether ketone) is amorphous and soluble in THF, the reaction is fairly rapid (hours) but is much slower (days) when the starting polymer is semicrystalline, with only low solubility in THF. Quantitative desilylation of the resulting polymers is achieved by reaction with excess fluoride ion, affording poly(arylene-trifluoromethylcarbinol)s. These extremely polar polymers are readily soluble in protic solvents such as methanol or ethanol to give solutions from which tough, coherent films may be cast by evaporation in air. Despite the evidently high polarity of the bulk polymers, the surfaces of cast films are relatively hydrophobic, with static water contact angles of similar to 90 degrees. Surface analyses by XPS are consistent with enrichment of the polymer-air interface in CF, groups.