Ana Maria Bago Rodriguez
Emulsions stabilized with polyelectrolyte complexes prepared from a mixture of a weak and a strong polyelectrolyte
Bago Rodriguez, Ana Maria; Binks, Bernard P.; Sekine, Tomoko
Professor Bernard P Binks B.P.Binks@hull.ac.uk
Professor of Physical Chemistry
The possibility of stabilizing emulsions with polyelectrolyte complexes (PEC) obtained from the interaction of two non-surface-active oppositely charged polyelectrolytes (PEL) is described. Poly(allylamine hydrochloride) (PAH) and poly(4-styrene sulfonate) sodium salt are selected as the weak cationic and the strong anionic polyelectrolyte, respectively. Aqueous polymer mixtures are investigated by light scattering to determine the size of the complexes and whether precipitation or complex coacervation occurs. The effects of PEL mixing ratio, pH, and PEL concentration are studied in detail. By increasing the pH, the transition precipitate–precipitate/coacervate–coacervate–polymer solution is observed. At low pH, both PEL are fully ionized and therefore precipitates (soft particles) arise as a result of strong electrostatic interactions. By increasing the pH, the degree of ionization of PAH decreases and weak electrostatic interactions ensue, supporting the formation of coacervate droplets. The most stable oil-in-water emulsions are prepared from aqueous mixtures around charge neutralization. Although emulsions can be prepared from coacervate droplet dispersions, their coalescence stability is worse than those stabilized by soft PEC particles. By increasing the PEL concentration, the average droplet diameter decreases and the fraction of cream in the emulsion increases for emulsions prepared with PEC particles, following the limited coalescence model. However, at high concentrations, emulsion stability is slightly worse probably due to extensive aggregation of the particles. Viscous high internal phase emulsions can be prepared at low pH in which oil droplets are deformed. Here, PEC particles are detected only at the oil–water interface. At lower oil content, excess particles form a network in the aqueous phase aiding emulsion stability to coalescence.
|Journal Article Type||Article|
|Publication Date||May 21, 2019|
|Publisher||American Chemical Society|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Bago Rodriguez, A. M., Binks, B. P., & Sekine, T. (2019). Emulsions stabilized with polyelectrolyte complexes prepared from a mixture of a weak and a strong polyelectrolyte. Langmuir : the ACS journal of surfaces and colloids, 35(20), 6693-6707. https://doi.org/10.1021/acs.langmuir.9b00897|
|Keywords||Spectroscopy; Electrochemistry; General Materials Science; Surfaces and Interfaces; Condensed Matter Physics|
This file is under embargo until May 8, 2020 due to copyright restrictions.
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