Copolymers of N,N-Dimethylacrylamide and 2-(N-ethylperfluorooctanesulfonamido)ethyl Acrylate in Aqueous Media and in Bulk. Synthesis and Properties

Abstract

Hydrophobically modified (HM) associating water-soluble poly(N,N-dimethylacrylamide) (PDMA) polymers were prepared by free-radical copolymerizations of DMA and 2-(N-ethylperfluorooctanesulfonamido)ethyl acrylate (FOSA). The polymerizations were carried out in deionized water in the presence of ammonium persulfate at 50 °C or in bulk in the presence of AIBN at 65 °C. The copolymerization kinetics monitored simultaneously by 19F and 1H NMR spectroscopy indicates that DMA and FOSA is incorporated at the same relative rates throughout the polymerization. The viscosities of the polymer solutions were measured on a Brookfield viscometer and an Ubbelohde capillary viscometer. A large viscosity enhancement was observed in comparison with PDMA homopolymer solutions. The effects of polymer concentration, shear rate, surfactants, salts, and temperatures on the reduced and Brookfield viscosities were investigated. Interestingly, the aqueous solution of the copolymer prepared in bulk exhibits both hydrophobic interaction and polyelectrolyte effects in the presence of anionic perfluorocarbon surfactant. The resulting polymers were also characterized by size exclusion chromatography and by 1H and 19F NMR spectroscopy.

Synthesis and solution properties of fluorocarbon‐modified poly( N,N ‐dimethylacrylamide)

“…This was observed previously for the higher molecular weight emulsion PDMA/FX-13 copolymers and for the FX-13 and FX-14 acrylamide copolymers of this type. 13,14 This behaviour is consistent with the increasing association of progressively contracted coils as the comonomer content increases.…”

“…They are lower than the M v values of the emulsion copolymers (M v = 2 Â 10 6 ± 5 Â 10 6 g mol À1 ) prepared in water by ammonium persulfate initiated polymerization of DMA and FX-13 at 50°C; 14 however they are higher than that of the AIBN initiated PDMA±FX-13 copolymers (M v = 3 Â 10 5 ±7 Â 10 5 g mol À1 ) obtained by bulk copolymerization. 14 The lower aqueous intrinsic viscosities of co-3-2 to co-3-5 would seem to be consistent with increasingly strong intramolecular association of the per¯uorooctyl groups as the comonomer content increases from 0.08 to 1.07 mol%. 7 An estimation of the concentration of per¯uorocar-bon groups within the polymer coils is of interest.…”

“…Poly(N,N-dimethylacrylamide) (PDMA) is a well known water-soluble polymer that is widely used in the paper, textile and coating industries. Recently, Xie and Hogen-Esch 14 reported the synthesis and solution properties of FX-13-modi®ed PDMA by per¯uorocarbon surfactant-mediated emulsion copolymerization and bulk copolymerization. The aqueous viscosities of the emulsion copolymers formed were found to be much higher than those of the bulk PDMA copolymers, partly because of the lower molecular weights of the bulk copolymers.…”

Theoretical Study of Molecular Association and Thermoreversible Gelation in Polymers

“…One series of APs are based on poly(ethylene oxide) chains (referred to as PEO), being modified by short alkyl chains, [70][71][72][73][74]125 propyrene oxide (or butylene oxide) chains 77 and fluorocarbon chains. [78][79][80][81] Hydrophobes are either period-ically or randomly attached on a polymer chain. The simplest one is a telechelic polymer carrying two hydrophobes at the chain ends.…”

“…The effects can be summarized into the following four categories: (i) Conformational transition of polymers such as coil/globule transition 135,136 and coil/rod transition, 137,138 (ii) Expansion and shift of the phase separation region on the polymer/solvent phase plane, 139 (iii) Formation of composite microphases, 140 (iv) Shift of the sol/gel transition line [141][142][143] and modification of the rheological properties. 71,80,82 When polymers carry small fractions of hydrophobic groups, effects are dramatically enhanced, because the ability of surfactant binding is enhanced by the hydrophobic interaction between polymer hydrophobes and surfactant hydrophobes. A profound influence of added surfactants on the rheological properties has been reported.…”