Study of cryostructuration of polymer systems. XII. Poly(vinyl alcohol) cryogels: Influence of low-molecular electrolytes

✍ Scribed by V. I. Lozinsky; L. V. Domotenko; A. L. Zubov; I. A. Simenel

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 724 KB
• Volume: 61
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960912)61:11<1991::aid-app13>3.0.co;2-2

✦ Synopsis

The influence of the presence of low-molecular electrolytes in initial solutions of poly(viny1 alcohol) (PVA) on the results of cryotropic gelation of the polymer (gelation caused by the freezing-thawing) and on the swelling characteristics of PVA cryogels prepared in a saltfree medium were studied. The reinforcing ability of the electrolytes with respect to the gel strength for both alkaline element cations and simple low-molecular anions has been shown to be in agreement with the positions of these ions in corresponding lyotropic (Hofmeister) series. Namely, the ions (chaotropic ones), which are capable to interfere the Hbonding, disturbed somewhat the cryotropic gel-formation of PVA and facilitated the marked additional swelling of cryogels preliminary prepared in pure water medium, whereas the ions (antichaotropic ones), which are capable to promote the H-bonding, caused the formation of reinforced cryogels and resulted in the shrinking of cryogels prepared without salt additives. More pronounced eflects were observed for anions as compared with cations. Some anomalous swelling behavior of PVA cryogel in Cs+-containing solutions was supposed to be associated with the formation of weak chelates. In addition to antichaotropic inorganic salts like NaF, rather high salting-out eff'ects in respect to PVA were exhibited by wellsoluble amino acid salts: glycine zwitter-ions, lysine monochlorohydrate, and monosodium aspartate. CCI 1996 .