Complexation of poly(vinyl alcohol)–congo red aqueous solutions. 3. Dynamic light scattering study

✍ Scribed by Fumiyoshi Ikkai; Mitsuhiro Shibayama; Shunji Nomura; Charles C. Han

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 563 KB
• Volume: 34
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19960415)34:5<939::aid-polb12>3.0.co;2-c

✦ Synopsis

Mesoscopic structures of poly(viny1 alcohol)-Congo red (PVA-CR) complexes in aqueous solutions were investigated in terms of dynamic light scattering (DLS) technique. The intensity-intensity time correlation function, g"'(t), was analyzed with an equation including a single and a stretched exponential function. Two diffusion coefficients, D, (fast) and D, (slow) were evaluated. D, was converted to the apparent correlation length, tepp, via the mode-mode coupling hypothesis. The estimated tapp was insensitive to the sol-to-gel transition but decreased with CR concentration. This change may be related to the electrostatic screening effect. On the other hand, D, oscillates with increasing CR concentration a t a specific PVA concentration range. This explains well the reentrant sol-gel-sol-gel transition behavior observed in the PVA-CR systems. D, seems to represent the mobility of the PVA-CR complexes, which annihilates at the gel point. 0 1996 John