Unperturbed dimensions and the theta temperature of dextran in aqueous solutions

✍ Scribed by Ali Güner

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 125 KB
• Volume: 72
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19990516)72:7<871::aid-app2>3.0.co;2-r

✦ Synopsis

Intrinsic viscosity measurements were carried out on dextran samples (of different molecular weights) in aqueous solutions at 25, 28, 31, 34, 37, 40, and 43°C. The extrapolation methods were used for the data; they gave unperturbed dimensions, K 0 , of the chain. The unperturbed root-mean-square end-to-end distance ͗r 2 ͘ 0 1/ 2 calculated for the polymer samples in water indicate that the polymer coils are slightly contracted in this solvent as the temperature is increased. The long-range interaction parameter, B, was also determined. In aqueous dextran solutions, this showed a significant decrease in the long-range interactions between 25 and 43°C. The values of ⌰ ϭ 317.82 and 316.57 K were obtained from the temperature dependence of the interaction parameter B in the Kurata-Stockmayer-Fixman and Berry equations. Calculated values were interpreted mainly on the basis of hydrogen-bond formation between polymer segments and dextran-water molecules in solution.