title: Flocculation with poly(ethylene oxide)/tyrosine-rich polypeptide complexes.
abstract: New insights into the mechanism for the flocculation of aqueous colloids by the sequential addition of a 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 adsorb onto the surfaces of the target colloidal particles. Flocculation will occur if PEO/cofactor complex on one particle will bind to adsorbed complex on a second particle; i.e., if the complexes are sticky. The proposed mechanism was illustrated by flocculation experiments with precipitated calcium carbonate, very high molecular weight PEO, and a polypeptide cofactor called PEY1 which was a 1:1 random copolymer of l-glycine and l-tyrosine. Independent measurements of the PEO/PEY1 complex properties, in the absence of 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 unbound PEY1 or PEO segments.
authors.affiliation: Department of Chemical Engineering, McMaster University, 307-1710 Main Street West, Hamilton, Ontario L8S 1G6, Canada.
authors.forename: Chen
authors.initials: C
authors.lastname: Lu
authors.forename: Robert
authors.initials: R
authors.lastname: Pelton
mesh_terms: D000327:Adsorption; D002119:Calcium Carbonate / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D005427:Flocculation; D005998:Glycine / Q000737:chemistry; D007700:Kinetics; D008031:Lignin / Q000737:chemistry; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D003102:Colloids; D010455:Peptides; D012996:Solutions; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D014443:Tyrosine; D008031:Lignin; D002119:Calcium Carbonate; D005998:Glycine