Novel PVA-based polymers showing an anti-Hofmeister Series property
✍ Scribed by Jianquan Wang; Mitsuru Satoh
- Publisher
- Elsevier Science
- Year
- 2009
- Tongue
- English
- Weight
- 206 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0032-3861
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✦ Synopsis
A series of poly(vinyl alcohol)-trimellitate (PVA-T) polymers with different esterification degrees (ED: 82, 61, and 32 mol%) were prepared through the esterification of PVA and trimellitic anhydride (TA). Solubilities of these polymers and the swelling properties of PVA-T hydrogels, which were prepared by crosslinking with ethylene glycol diglycidyl ether (EGDGE), were investigated in various salt solutions comprising of SO 4
The PVA-T polymers proved to have larger solubilities in salt solutions (1 M) than in pure water, and the ionic ''salting-in'' effect was significant in order of SO 4 2À > SCN À > Cl À for anions, and Li
for cations, regardless of their ED values. The PVA-T hydrogels also showed corresponding swelling properties; they significantly swelled in sulfate solutions of medium concentration (0.1-1 M), while in other salt solutions no appreciable swelling occurred. The marked salting-in effects exerted by sulfate anion, which is otherwise a typical ''saltingout'' agent, means that PVA-T polymers have an ''anti-Hofmeister Series'' (anti-HS) property. This is naturally ascribed to the trimellitic acid group because the degree of swelling in sulfate solutions was more significant for PVA-T with higher ED values; the combination of p-electron system and acidic protons seems to be essential to endow polymers with the anti-HS property.