In a method of preparing an 
aqueous dispersion selected from drilling fluids, hydraulic 
cement compositions, mineral 
pigment containing coatings, and 
papermaking furnishes or in a method of preparing a melt extrudate, the improvement comprising: a) producing a 
copolymer of 
vinyl alcohol (VOH) and 2-acrylamido-2-methyl 
propane sulfonic acid or a salt of such acid (AMPS) by steps including continuously feeding with agitation, 
vinyl acetate (VAM) and AMPS as comonomers, a free radical yielding 
polymerization initiator, and a 
solvent for said comonomers, initiator, and 
copolymer resulting from the copolymerization of said comonomers, maintaining the resulting reaction 
mass in said first 
reaction zone under 
polymerization conditions for a 
residence time sufficient for a major proportion of AMPS fed to said first 
reaction zone to polymerize, continuously feeding reaction 
mass from said first 
reaction zone with an additional supply of AMPS to a second reaction zone, maintaining the reaction 
mass in the second reaction zone for a 
residence time sufficient to polymerize a major proportion of the AMPS added to the second reaction zone, continuously withdrawing reaction mass from the second reaction zone, separating 
copolymer of VAM and AMPS from the latter reaction mass, and saponifying by 
hydrolysis and / or alcoholysis a major proportion of the acetate groups in said copolymer to form a copolymer of VOH and AMPS; and b) incorporating the saponified copolymer into the 
aqueous dispersion or melt extrudate.