Interactions of fluorocarbon-modified poly(acrylic acid) with a cationic fluorocarbon surfactant

The physicochemical properties of mixed systems of fluorocarbon-modified poly(acrylic acid) (FA) with a cationic fluorocarbon surfactant, bis(2-hydroxyethyl)(2-hydroxy-3-perfluoro-octylpropyl)methylammonium chloride (DEFUMAC), have been investigated by surface tension, fluorescence, solubility, and 19F NMR spin–lattice relaxation measurements. The result obtained from the surface tension measurement indicates that surface DEFUMAC–FA complexes are formed by strong electrostatic attraction at pH 10, while they are formed by hydrogen bond at pH 4. However, hydrophobic interaction is hardly observed at both pHs. In the bulk properties estimated from fluorescence and solubility measurements, DEFUMAC–FA complexes exhibit large solubility capacity for fluorocarbon compounds when the content of fluorocarbon in FA increases. Moreover, the result obtained from the spin–lattice relaxation time measurement suggests that the mobility of hydrophobic end group of DEFUMAC for DEFUMAC–FA complex at pH 10 is more restricted than that at pH 4.