Acid–base behavior of poly (vinylpyrrolidone–vinylimidazole) copolymers

✍ Scribed by Irving M. Klotz; Mark L. Lyndrup

• Publisher: Wiley (John Wiley & Sons)
• Year: 1968
• Tongue: English
• Weight: 528 KB
• Volume: 6
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1968.360061004

✦ Synopsis

Copolymers of vinylimidazole and vinylpyrrolidone containing 0.7-24% of the former residue have been prepared. Titration behavior was examined over a range of temperature and at several ionic strengths. Intrinsic pK's, corrected for electrostatic effects, are independent of mole fraction of imidazole residue in the copolymer. Pu'evertheless they are about 1.15 pK units lower than in the corresponding model small molecule, N-ethylimidazole. Enthalpies and entropies of ionization in the copolymer are changed by ionic strength. It is apparent that the charged state of an N-ethylimidazole residue placed in a macromolecular matrix is destabilized relative t o the uncharged state because of changes in the local polymer or solvent environment.

* Similar investigations, but less extensive, have been carried out by Kopple.