New Fluorocarbon-Containing Hydrophobically Associating Polyacrylamide Copolymer

Abstract

The synthesis of polyacrylamide copolymers containing fluorine-containing acrylates 1, 2, 4 or 5 or silicone-containing methacrylate 6 was carried out by emulsion polymerization using persulfate as initiators and ionic perfluoro surfactants. The Brookfield viscosities of these copolymers, especially those containing 1 or 2, were much higher than the laurylacrylate (3) containing co polymer. The comonomer content of the 1 or 2 containing copoly mers that were most strongly viscosifying was only .07-.28 mole percent, well below that of the corresponding copolymers contain ing 3. Viscosity increases of the 1 and 2 copolymers, observed upon increases in temperature or NaCl concentration were consis tent with association of these copolymers through intermolecular hydrophobic binding. Reduced viscosity or dynamic light scattering studies are consistent with the existence of polymer assemblies above polymer concentrations of about 100 pm. Addition of surfac tants water miscible organic solvents or increasing shear rate was shown to lead to sharp viscosity decreases consistent with the proposed model.The replacement of hydrocarbon-by perfluoroalkyl groups in hydrophobically associating polymers 1 is of potential interest since the hydrophobic character of perfluoroalkyl groups is more pronounced compared to their hydrocarbon analogs. 2 Thus, the critical micelle concentrations of fluorocarbon surfactants generally are significantly lower than the hydrocarbon analogs of the same chain length and surface tensions of fluorocarbon surfactant solutions are also much lower. 2 -3 Also hydrophobic bonding of fluorocarbon surfactants to β-cyclodextrines is much stronger (about 300 times) compared to similar hydrocarbon containing surfactants. 4 Significantly, the latter process is enthalpy driven (ΔΗ = -9.0 kcal/mole, AS = -12 eu) whereas the bonding of the fluorocarbon

Associative properties of perfluorooctyl end‐functionalized polystyrene–poly(ethylene oxide) diblock copolymers

“…The study of associative polymers has recently drawn considerable interest due to their unusual rheological properties,1–3 which are due to the presence of incompatible4–7 groups, for example, hydrophilic and hydrophobic groups, and/or to the strong intermolecular association, ie hydrophobic association of one of the groups. The elucidation of structure–properties relationships of these associative polymers8–12 requires well‐defined polymer structures.…”

Synthesis and Linear Viscoelasticity of Fluorinated Hydrophobically Modified Ethoxylated Urethanes (F-HEUR)

“…A maximum of efficiency was observed with POE with a degree of polymerization close to 500 (M n ) 20 000). 16 Hogen-Esch et al have reported that perfluoroalkylmodified water-soluble polymers (hydroxyethylcellulose, 14 polyacrylamides, 8,18 or POE 19 ) are much more effective thickeners compared to the corresponding hydrocarbon derivatives. The enhanced viscosity can be explained by the clustering and self-assembling of the perfluorinated groups.…”

Fluorescence Studies of Hydrophobic Association of Fluorocarbon-Modified Poly(N-isopropylacrylamide)

“…It is known that perfluoroalkyls are more hydrophobic than their hydrocarbon analogues. 27 Because of this, Zhang et al [28][29][30] studied copolymers based on polyacrylamide with a small amount of an acrylate or methacrylate with a fluorocarbon-containing group. Such polymers exhibited more pronounced hydrophobic association than the corresponding hydrocarbon-substituted copolymers.…”