Highly hydrophobically modified polyelectrolytes stabilizing macroemulsions: relationship between copolymer structure and emulsion type |
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Authors: | P Perrin N Monfreux F Lafuma |
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Institution: | (1) Ecole Supérieure de Physique et Chimie Industrielles de Paris CNRS Université Pierre et Marie Curie UMR 7615 Physico-Chimie des polymères 10, rue Vauquelin, F-75 005 Paris, France, FR;(2) Laboratoire de Physico-chimie Macromoléculaire ESPCI 10, rue Vauquelin F-75231 Paris Cedex 5 France, FR |
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Abstract: | The types of emulsions, oil (n-dodecane) in water (O/W) or water in oil (W/O), stabilized with highly hydrophobically grafted linear poly(sodium acrylate)s,
were investigated as a function of polymer chemical architecture. Consequently, a large number of macroemulsifiers, covering
a wide range of hydrophobicity, were synthesized by changing the degree of grafting (τ), length (n) and type (single- versus twin-tailed) of the hydrophobic moiety. Monovalent salt (NaNO3) concentration was used as a probe to adjust and hence to estimate the hydrophile-lipophile balance (HLB) of each copolymer.
τ, n, type of graft and electrolyte concentration were identified as field parameters to control emulsion type. In general, decreasing
either τ or n was found to favor the formation of direct emulsions. Inverse dispersions were preferentially formed with twin-tailed rather
than single-tailed copolymers. Moreover, the types of emulsions stabilized with well-balanced polyelectrolytes can be flipped
from O/W to W/O with increasing salt concentration. Finally, following the Davies concept, a HLB scale for polymers was created
from a comparison with surfactants of nearly identical chemical structure.
Received: 15 June 1998 Accepted: 12 August 1998 |
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Keywords: | Emulsion type amphiphilic polymer polyelectrolyte polymeric surfactant balanced copolymers HLB scale |
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