Emulsions Stabilized with Polyelectrolyte Complexes Prepared from a Mixture of a Weak and a Strong Polyelectrolyte

Abstract

The possibility of stabilising 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 (PSSNa) 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 ionised and therefore precipitates (soft particles) arise as a result of strong electrostatic interactions. By increasing the pH, the degree of ionisation 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 neutralisation. Although emulsions can be prepared from coacervate droplet dispersions their coalescence stability is worse than those stabilised 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.

Electrochemical Stimulation of Water–Oil Interfaces by Nonionic–Cationic Block Copolymer Systems

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Intrinsic Effect of Nanoparticles on the Mechanical Rupture of Doubled‐Shell Colloidal Capsule via In Situ TEM Mechanical Testing and STEM Interfacial Analysis

“…There are several strategies to incorporate the nanoparticles on the capsule shell [6] , and Pickering emulsion templated assembly is considered to be a facile and efficient approach [6][7] . A recent review on the preparation of capsules from particle-stabilized or Pickering emulsions has been discussed [8] .…”

ElectroSens Platform with a Polyelectrolyte-Based Carbon Fiber Sensor for Point-of-Care Analysis of Zn in Blood and Urine

“…An unstable behavior of the adsorbed layers with 1.6 to 12 mg/mL Hg 2+ explains PE complexation with others and breaks away from the surface. This PE complexation depends on the salt concentration in the adsorbed PE layers. , …”