Swelling behaviour of poly(?-hydroxyacrylic acid) gel

✍ Scribed by Tamura, Toru; Yoshida, Shigeto; Miyamoto, Yasushi; Kawauchi, Susumu; Satoh, Mitsuru; Komiyama, Jiro

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 126 KB
• Volume: 49
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(200002)49:2<147::aid-pi315>3.0.co;2-o

✦ Synopsis

Poly(a-hydroxy acrylic acid) (PHA) and poly(acrylicacid) (PAA) gels were prepared by irradiating the respective 15 wt% aqueous solutions with g-rays. Swelling ratios for PHA gel were measured as a function of pH and divalent cation (Mg 2 , Ca 2 , Mn 2 , Co 2 , Ni 2 , Cu 2 ) concentration C 2 in the external solution to provide a comparison with the results for PAA gels. It was found that the swelling ratio of PHA gel steeply increases between pH 2 and 4, followed by a gradual swelling in the higher pH region. The corresponding steep swelling of PAA gel was observed at pH 3±6. Cation speci®city in the equilibrium swelling ratio at a lower C 2 value (1.0 Â 10 À3 M) was approximately consistent with the binding selectivity in the solution system. Typically, the swelling ratio of PHA gel in the presence of Ca 2 was signi®cantly lower than in the Mg 2 system, while the difference was slight for PAA gel. The response of the swelling ratio to changes in pH and C 2 was analysed as a ®rst order relaxation to estimate the time constants. The (de)swelling kinetics measured by both the pH and C 2 jump were qualitatively interpreted in terms of main-chain stiffness and intermolecular hydrogen bonding in the respective polymers.