Conformation of polyacrylamide in aqueous solution with interactive additives and cosolvents

Abstract

ABSTRACT:The viscosity of polyacrylamide (PAM) dilute aqueous solutions with NaCl, glucose, and SDS as additives was measured by Ubbelohde viscometry. There was linear relationship between reduced viscosity vs. PAM concentration in aqueous solutions. The Huggins constant k and intrinsic viscosity [] were used to study the conformation of the polymer chains and the degree of polymer-solvent interaction. In addition, the viscosity of diluted PAM solutions in water with acetone, ethanol, DMF, and ethylene glycol as cosolvent was measured. It was found that the polymer chain conformation contracted as the acetone, ethanol, and DMF cosolvent composition ratio increased, but there was no distinguishing difference between water-ethylene glycol compositions. The solution properties of PAM were used to estimate the swelling properties of PAM gel in the same external conditions, as gel is formed by crosslinking of linear polymer. In good solvent the polymer chain should be expanded, and gel is expected to have large swelling ratio. In water cosolvent systems, when the linear polymer chain underwent coil-globule transition, PAM gel should have volume phase transition under corresponding external conditions.

A novel thermoviscosifying water‐soluble polymer: Synthesis and aqueous solution properties

“…For instance, at 40 C, the viscosity of P(AM-co-MPAD) solutions is enhanced from 9.2 to 118.3 mPa s when increasing KCl level from 1 to 5%. Nevertheless, when KCl concentration is above 1%, the viscosifying effect seems to be unaffected by KCl concentration when temperature is higher than 60 C. As seen from Figure 7(b), one can find that at lower salinity (<2%) 0 the viscosity of PAM solution decreases with increasing KCl concentration; but at higher salinity, see, above 2%, the viscosity increases with increasing KCl concentration, which is in line with the results reported by Shanks et al, 50 and can be attributed to the competition of salting-out effect of nonpolar section and salting-in effect of amide groups in the PAM molecule.…”

“…A total of 0.5 mL of 1% (w/v) KPS aqueous solutions was then injected. The polymerization was proceeded at 50 C with a thermostatically controlled water circulating bath under N 2 atmosphere for 10 h. The resulting product was obtained by dropwise addition into fivefold excess of acetone and repeatedly washed with acetone, following with freeze-drying, and 8.15 g of the final product was obtained. For comparison, homopolyacrylamide, PAM, was prepared under the identical conditions.…”

Solubility study of polyacrylamide in polar solvents

“…Previously, the conformation study by the viscosity measurement of PAM diluted water and EG solutions showed that the PAM chains in water was more extended than in EG, which means that a PAM gel should swell more in water than in EG. 17 This solubility and viscosity study provided the same conclusion from a different point of view. The values of ⌬G 121 for acetone, ethanol, and DMF were much smaller than 0, so it can be concluded that the PAM molecules cannot repel each other in these three solvents; there would be no swelling when PAM gel is placed in these three solvents.…”

“…Previously, viscosity measurements were used to compare the polymer chain conformations; however, this method did not show the slight differences. 17 Figure 1 also demonstrates that the acetone cosolvents have the smallest polarity compared with the other three cosolvents. Therefore, acetone will be the best precipitant for PAM.…”

Properties of hydrophobically modified polyacrylamide with low molecular weight and interaction with surfactant in aqueous solution

“…30 Because of the presence of hydrophobes in aqueous solution, the Huggins constant of a modified polymer is expected to be higher than that of its unmodified analogue. However, the trend is reversed here and it is proposed that this is due to the association of the hydrophobic domains.…”