Michel Viguier

Fluorocarbon associative polymers

Fluorocarbon associative polymers modified along the backbone or at the extremities by hydrophobic groups are reviewed with respect to their association and rheological properties in aqueous solutions. Above a threshold concentration corresponding to the formation of a reversible network structure, the solutions behave as physical gels. In this review, it is shown that the viscoelasticity of fluorocarbon associative polymer gels is enhanced with respect to that of hydrocarbon analogues. For polymers substituted at the extremities (telechelics), significant progresses have been made in recent years concerning the microstructure, the phase behavior and the rheology of the gel state. Telechelics in solutions are forming multiconnected structures, which dynamical features are in good agreement with those of transient network models.

Kinetics of homopolymerization of fluorinated acrylates, 5. Influence of the spacer between the fluorinated chain and the ester group

The synthesis of various fluorinated acrylates CH 2 =CHCOO(CH 2 ) p C n F 2n+1 and their kinetics of radical homopolymerization are presented. The fluoroacrylated monomers have been prepared in two steps by acrylation of the corresponding halogenated alcohols produced by radical addition of perfluoroalkyl iodides(C n F 2n+1 I) to ω-hydroxylated alkenes. The fluorinated acrylates differ from each other in the nature (branched or linear) and the length (n ranging from I to 8) of the fluorinated chain and in the nature of the spacer between this fluorinated chain and the ester group (p ranging from I to 11). The kinetics of polymerization led to the determination of k 2 p /k te . These values were comparcd with those of commercially available fluorinated acrylates and were found to depend upon both the spacer length and the nature of the fluorinated group.

Synthesis and characterization of model fluoroacylated poly(ethylene oxide)

Abstract The modification of hydroxytelechelic poly(ethylene oxide)s (PEO) of molecular weights 10.000, 20.000 by a fluorinated acid leading to fluoroacylated poly(ethylene oxide)s (FA-PEO) is described. The one pot process involving the in situ generation of a fluorinated anhydride by reaction with N , N -dicyclohexylcarbodiimide (DCC) leads to complete modification of hydroxy end-groups. The reaction is catalyzed by dimethylaminopyridine (DMAP). A method, based on 19 F-NMR spectroscopy, has been developed for the detection and titration of residual PEO hydroxy end-groups.

Structure and wettability of methacrylic polymers with fluorinated side chains

Abstract Surface properties of methacrylic homopolymers and copolymers with a random distribution of pendant perfluorinated groups RF  CnF2n+l have been studied. These polymers are obtained by radical polymerization in solution or emulsion of fluorinated monomers (MF) CH2  C (CH3) CO2 (CH2)2 RF with various hydrogenated comonomers (MH). Surface tensions are estimated according to the length of RF groups (n = 4, 6, 8), the fluoromonomer concentration [ MF ] in copolymers and the chemical structure of comonomers MH (MMA, BMA …), by different methods: Zismans (γC), geometric and harmonic mean approximation. Wettability measurements can provide useful information about the structure of polymeric surfaces. The tensiometric method used for wetting measurements reveals an abnormally large hysteresis effect between advancing and receding contact angles when the polymer surface is in contact with water. This effect is markedly decreased by the length of the RF group from n = 4 or 6 to 8 and by the concentration of fluoromonomer units in copolymers. The evolution of the surface properties of the polymer in contact with a polar liquid (water) can be explained by the reorganization and the reorientation of hydrophilic moieties of the macromolecules at the interface. At the polymer — air interface the fluorinated chain packing control the surface wettability. Hydrophilic ester groups of methacrylic units are buried in the bulk of the polymer, thus the polymer surface is different from its bulk. The evolution of surface energy cannot be explained by adsorption or absorption of water. A study by DSC has therefore been undertaken to correlate hysteresis with the potential organization of RF groups at the polymer — liquid interface and crystallinity of fluoropolymers.