Zwitterionic polymers—III. Salt effects on the solubility of poly(vinyl sulphobetaines) and poly(vinyl betaines) in aqueous solution

✍ Scribed by Thomas A. Wielema; Jan B.F.N. Engberts

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 343 KB
• Volume: 26
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(90)90220-x

✦ Synopsis

Critical salt concentrations were measured for dissolution of poly [1-vinyl-3-(2-sulphoethyl)imidazolium betaine] and poly[1-vinyl-3-carboxy-ethylimidazolium betaine] in aqueous solutions. It was found that the critical salt concentration varies considerably with the nature of the anion and follows a Hofmeister series. The differences within a series of cations were rather small and only by changing a metal cation to a tetraalkylammonium cation was there a considerable change in critical salt concentration. These results are interpreted in terms of differences in hydration of the individual charges of the zwitterionic polymer. By comparison of the critical salt concentrations within a series of poly(vinyl sulphobetaines) with different numbers of methylene units between the charges, evidence was obtained for the operation of intramolecular Coulombic interactions as the dominating factor in the solubility behaviour of the zwitterionic polymers in aqueous solutions.