Temperature Dependence of Soret Coefficient in Aqueous and Nonaqueous Solutions of Pullulan

Kishikawa, Y.; Wiegand, S.; Kita, R.

doi:10.1021/bm9013149

Journal Article

PreJuSER-9194

Temperature Dependence of Soret Coefficient in Aqueous and Nonaqueous Solutions of Pullulan

Kishikawa, Y. ; Wiegand, S.FZJ* ; Kita, R.

2010
American Chemical Soc. Columbus, Ohio

Biomacromolecules 11, 740 - 747 (2010) [10.1021/bm9013149]

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Please use a persistent id in citations: http://hdl.handle.net/2128/4669 doi:10.1021/bm9013149

Abstract: We present experimental results of the temperature dependence of the Ludwig-Soret effect for pullulan solutions. The Soret coefficients of 5.0 g L(-1) pullulan in water and in dimethyl sulfoxide (DMSO) were determined in the experimental temperature range between 20.0 and 50.0 degrees C by means of thermal diffusion Forced Rayleigh scattering (TDFRS). The sign of the Soret coefficient of pullulan in water is negative at room temperature, which indicates that the pullulan molecules migrate to the warm side of the fluid. The Soret coefficient of pullulan increases steeply with increase of the solution temperature and shows a sign change from negative to positive at 41.7 degrees C. The positive sign of the Soret coefficient means the pullulan molecules move to the cold side. In contrast to the aqueous solution, the solution of pullulan in DMSO shows a very weak temperature dependence of the Soret coefficient and has always a positive sign. In addition to the TDFRS experiments, we also performed light scattering (LS) experiments for the pullulan solutions under homogeneous temperature condition in a temperature range between 20.0 and 55.0 degrees C. The thermodynamic properties of pullulan solutions obtained by LS show no pronounced correlation with the thermal diffusion behavior of pullulan. These results indicate the existence of a special role of interactions due to solvation on the temperature dependence of the thermal diffusion behavior of polysaccharide solutions.

Keyword(s): Dimethyl Sulfoxide: chemistry (MeSH) ; Glucans: chemistry (MeSH) ; Light (MeSH) ; Scattering, Radiation (MeSH) ; Solutions (MeSH) ; Temperature (MeSH) ; Thermodynamics (MeSH) ; Water: chemistry (MeSH) ; Glucans ; Solutions ; Dimethyl Sulfoxide ; Water ; pullulan ; J

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Note: The authors thank Jail Dhont and Hartmut Kriegs for their kind Support and Shin Yagihara and Naoki Shinyashiki for their kind help. The sample (pullulan) donation by Hayashibara Co. is gratefully acknowledged. This work is partially supported by Deutsche Forschungsgemeinschaft (Grant Wi 1684) and by the Ministry of Education, Science, Sports and Culture, Japan (Grant-in-Aid for Scientific Research).

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