WATER-SOLUBLE COPOLYMERS .56. STRUCTURE AND SOLVATION EFFECTS OF POLYAMPHOLYTES IN DRAG REDUCTION

Water-soluble polyampholytes based on acrylamide (AM), sodium 2-acryla mido-2-methylpropanesulfonate (NaAMPS), (2-acrylamido-2-methylpropyl)t rimethylammonium chloride (AMPTAC), sodium 3-acrylamido-3-methylbutano ate (NaAMB),and 2-methylpropyl)dimethylammonio)-1-propanesulfonate (AM PDAPS) have been synthesized and characterized. The molecular weights of the polymers range from 1.4 X 10(6) to 21.5 x 10(6). Almost all the polyampholytes showed higher intrinsic viscosities at higher solvent ionic strength. The drag reduction behavior of high and low charge den sity polyampholytes and polybetaines was examined with a rotating-disk rheometer. All the polymers exhibited higher drag reduction at increa sed solvent ionic strength. The poly(sulfobetaines) (copolymers of AM and AMPDAPS) were found to be the most efficient drag reducers, and th e high charge density polyampholyte (copolymer containing 50 mol % eac h of AMPTAC and NaAMPS) was the least efficient. Experimental data ind icate that theoretical models of drag reduction should include paramet ers for polymer-solvent interactions and molecular associations.