The effect of phenol on the electrolyte flocculation of certain polymeric dispersions to thixotropic gels.

Aqueous dispersions of an acrylate-methacrylate, a water-insoluble copolymer, were prepared by a coacervation technique. Addition of sodium chloride (0.2 M) to the dispersion (10%, w/v) converted the system to a thixotropic gel which turns fluid on shaking and reverts to gel on standing. Phenol (0.03 M) inhibited the gelling effect of the electrolyte. Among the various phenolic compounds tested, phenol displayed the strongest and chlorocresol the weakest antigelling property. Sodium chloride reduced the electropotentials (index of particle-particle repulsiveness) of the polymer dispersions, while phenol increased the potentials. It is thought that the phenol solution acted as a dielectric which increased the interparticle repulsive potential, hence its antiflocculant effect.