SOLUTION PROPERTIES OF WATER SOLUBLE MACROMOLECULES FOR ENHANCED OIL RECOVERY APPLICATIONS (SCATTERING, DIFFUSION, VISCOMETRY)

Static and dynamic light scattering, dilute solution viscometry and membrane osmometry were used to determine the solution properties of two different series of copolymers. In order to examine the solution behavior of some dextran-g-acrylamide copolymers, a series of dextran polysaccharides and poly(acrylamides) differing in molar mass were evaluated. Dextrans were observed to obey the relationship D(,z) = 8.45 x 10('-5) M('-0.5) and (eta) = 0.366 M('0.39) where D(,z) is the translational z-average diffusion coefficient, (eta) the intrinsic viscosity and M the molecular weight. The exponents of both power laws indicate that dextrans were branched polymers and that water was a marginal solvent. Poly(acrylamides) were described by D(,z) = 1.25 x 10('-4) M('-0.54) and (eta) = 6.36 x 10('-3)M('0.79). The exponents indicated that poly(acrylamides) exhibit extensive excluded volumes and extended configurations in water. The series of dextran-g-acrylamide copolymers behaved abnormally in water. Systems with small numbers of branches tended to associate while samples with high branching densities exhibited polyelectrolyte behavior. Addition of 0.1 N KCl to aqueous solutions of the graft copolymers resulted in normal solution behavior. Associates species were disrupted by the action of the salt on hydrogen bonds. Unshielded ionizable groups were neutralized. Derived solution parameters did not depend on previously reported structural characteristics. In brine, linear copolymers of acrylamide with Na-2-acrylamido-2 methylpropane/sulfonate (AMPS) exhibited large excluded volumes. The configuration of these copolymers increased with an increase in AMPS content in the copolymers. Consideration of the solution properties of the two different copolymer series indicated that linear copolymers of acrylamide with AMPS may be useful in enhanced oil recovery applications. Dextran-g-acrylamide copolymers offer no distinct advantages.