Formation of poly(vinyl alcohol)–iodine complexes in solution

✍ Scribed by Hiroji Noguchi; Hirosi Jyodai; Syuji Matsuzawa

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 211 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199708)35:11<1701::aid-polb4>3.0.co;2-v

✦ Synopsis

The effect of the dissolved state of poly(vinyl alcohol) (PVA) molecules in water on the color development due to PVA-iodine complexes was investigated at each given PVA and iodine concentration using two kinds of syndiotactic-rich PVA (S-PVA) which are unstable in water because of the formation of intermolecular hydrogen bonds and form the complex easily. In the reaction mixtures prepared by mixing PVA solutions and an iodine solution, the color development was constant and independent of standing time of the PVA solution before the addition of iodine up to a certain time, after which it decreased with the standing time. The color development obtained with use of the PVA solution allowed to stand for a fixed time was higher for S-PVA with a lower s-(diad)%. In the case of the reaction mixture prepared by dissolving PVA in an iodine solution, the color development was higher for S-PVA with a higher s-(diad)%. The initial ratio of the I 0 5 /I 0 3 and the rate of decrease in the ratio of I 0 5 /I 0 3 were larger than those in the preceding case. The color development decreased for the PVA with an s-(diad)% of 58, whereas it increased for the PVA with an s-(diad)% of 61.3 with increasing propanol content, an inhibitor of gelation. From these results, the aggregates of PVA molecules have been assumed to play an important role in forming the complexes.