| Abstract
| - New insights into the mechanism for the flocculation of aqueous colloids by the sequential addition ofa water-borne phenolic polymer, called cofactor, followed by very high molecular poly(ethylene oxide)(PEO) are presented. It is proposed that PEO/cofactor complexes form in the aqueous phase and adsorbonto the surfaces of the target colloidal particles. Flocculation will occur if PEO/cofactor complex on oneparticle will bind to adsorbed complex on a second particle; i.e., if the complexes are sticky. The proposedmechanism was illustrated by flocculation experiments with precipitated calcium carbonate, very highmolecular weight PEO, and a polypeptide cofactor called PEY1 which was a 1:1 random copolymer ofl-glycine and l-tyrosine. Independent measurements of the PEO/PEY1 complex properties, in the absenceof calcium carbonate, were used to support the mechanism. In order for PEO/PEY1 complexes to be sticky,they must simultaneously have unbound PEY1 and polymer segments. With time the complexes deactivate(i.e., lose their stickiness) by a reconfiguration process which results in elimination of either unboundPEY1 or PEO segments.
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