Sizes and conformations of hydrophilic and hydrophobic polyelectrolytes in solutions of various ionic strengths

• Published in: Polymer science. Series A, Chemistry, physics Vol. 55; no. 12; pp. 699 - 705
• Main Authors: Pavlov, G. M., Okatova, O. V., Gavrilova, I. I., Ul’yanova, N. N., Panarin, E. F.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-12-2013
• Subjects: Chains (polymeric); Chemistry; Chemistry and Materials Science; Polymer Sciences; Solutions; Polymer Science Series; Intrinsic Viscosity; Salt Free Solution; Contour Length; Linear Charge Density
• ISSN: 0965-545X; 1555-6107
• DOI: 10.1134/S0965545X13120079

The hydrodynamic characteristics of macromolecules of a random copolymer of
N
-methyl-
N
-vinylacetamide and
N
-methyl-
N
-vinylamine hydrochloride containing 43.6% charged units in the molecular-mass range of 27 × 10
3
to 355 × 10
3
are studied. For solutions in 0.2 M NaCl, sedimentation and translational-diffusion coefficients are determined. For salt-free solutions and for solutions in 0.2 and 5.0 M NaCl, the intrinsic viscosities of the fractions are found. The lengths of the statistical segments of the chains are estimated in terms of the Gray-Bloomfield-Hearst theory. The behavior of the polycation, whose uncharged counterpart is a hydrophilic polymer, is compared to the behavior of poly(sodium 4-styrenesulfonate), whose uncharged counterpart is a hydrophobic polymer. The comparison is based on normalized scaling relations. It is shown that the level of compaction of macromolecules of strong polyelectrolytes at a high ionic strength is determined by the degree of hydrophobicity of their polymer chains. Polyelectrolytes based on hydrophilic polymers cannot be compacted into a preglobular state; their chains preserve a swollen coil conformation up to maximally high values of ionic strength.