Influence of denaturing agents on macromolecular coil dimensions of polyacrylamides in diluted aqueous solutions

Summary

A viscosimetric method was used to investigate the intramolecular association in diluted aqueous solution of two polyacrylamides. The concentration at which only intramolecular association take place were obtained from temperature effect on [η]. Addition of kalium iodide, a hydrogen bond breaker, increased [η]. As salt concentration was higher [η] became greater, proving that some part of intramolecular hydrogen bonds was broken. The values of [η] in 1 N salt solutions were in the order:

$${\text{HPO}}_{\text{4}}^{{\text{2 - }}} < {\text{H}}_{\text{2}} {\text{O}} < {\text{ Br}}^{\text{ - }} < {\text{NO}}_{\text{3}}^{\text{ - }} < {\text{I}}^{\text{ - }} = {\text{BrO}}_{\text{3}}^{\text{ - }} < {\text{ClO}}_{\text{3}}^{\text{ - }} = {\text{SCN}}^{\text{ - }} $$

. The dependence of the reduced viscosity at a constant concentration of 0.05 % polyacrylamide for the above mentioned salts, as well as for isopropyl alcohol, isobutyl alcohol, glycerine, urea, hydroxylamine hydrochloride, sodium acetate and sodium carbonate on additive concentration has been determined. The slopes of these diagrams were positive for hydrogen bond breakers and negative for hydrogen bond makers, showing that the first increased the macromolecular coil dimensions, whereas the last decreased them.