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Compression elastic modulus of neutral and protonated poly(N‐vinylimidazole) hydrogels
Author(s) -
Valencia Joaquín,
Baselga Juan,
Pacios Isabel E.,
Piérola Inés F.
Publication year - 2003
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200351024
Subject(s) - self healing hydrogels , protonation , aqueous solution , imidazole , polymerization , polymer chemistry , ionic bonding , ionic strength , modulus , chemistry , elastic modulus , compression (physics) , materials science , composite material , polymer , organic chemistry , ion
The compression modulus of poly(N‐vinylimidazole) (PVI) hydrogels synthesized by cross‐linking polymerization in aqueous solution, was measured at room temperature in several related systems: i) just after polymerization, ii) swollen at equilibrium in deionized water, iii) swollen in HCl (aq) (pH=2.5), iv) swollen in HCl (pH=2.5) and 1 M NaCl (aq) solution and v) swollen in H 2 SO 4 (pH=2.5) (aq) solution. Samples of the first and second groups are neutral whereas hydrogels of the other three groups are ionic because of protonation of basic imidazole groups. The experimental results were fitted with the Erman‐Monnerie theory, applied to compression measurements for the first time, to determine the phantom modulus, [ f ph *], and the parameter κ G which measures the constraining role of entanglements on the fluctuations of chains between knots.