TY - JOUR
T1 - Flory temperature and upper critical solution temperature of gelatin solutions
AU - Gupta, Amarnath
AU - Mohanty, B.
AU - Bohidar, H. B.
PY - 2005/5/1
Y1 - 2005/5/1
N2 - The Flory temperatures (θ) measured by turbidity experiments performed on gelatin solutions were found to be 12 ± 0.3, 13 ± 0.3, 14 ± 0.3, 14.5 ± 0.3, and 15 ± 0.3 °C for salt concentrations 0.1, 0.075, 0.05, 0.025, and 0 M (NaCl), respectively. Estimated persistence length (lp) of this weakly charged polyelectrolyte could be deduced from the Benoit and Doty (J. Phys. Chem. 1953, 57, 958) relationship with the approximation that this biopolymer assumes a compact near-globular shape at Flory temperature, implying lp = 9(Rh)2/(5Lm), where Lm is the contour length and Rh is the hydrodynamic radius. It was found that lp ≈ 2.2 ± 0.2 nm at room temperature (20 °C), invariant of salt concentration. The Flory expansion factor (α = Rh(T)/Rh(θ) = 1.5±0.2) was found to be almost constant. θ-Composition for this biopolymer was deduced from turbidimitric titration of aqueous gelatin solutions with the alcohols methanol, ethanol, 2-propanol, and tert-butyl alcohol. It appears that hydrophobic interactions play a crucial role in causing chain collapse at θ-temperature and composition.
AB - The Flory temperatures (θ) measured by turbidity experiments performed on gelatin solutions were found to be 12 ± 0.3, 13 ± 0.3, 14 ± 0.3, 14.5 ± 0.3, and 15 ± 0.3 °C for salt concentrations 0.1, 0.075, 0.05, 0.025, and 0 M (NaCl), respectively. Estimated persistence length (lp) of this weakly charged polyelectrolyte could be deduced from the Benoit and Doty (J. Phys. Chem. 1953, 57, 958) relationship with the approximation that this biopolymer assumes a compact near-globular shape at Flory temperature, implying lp = 9(Rh)2/(5Lm), where Lm is the contour length and Rh is the hydrodynamic radius. It was found that lp ≈ 2.2 ± 0.2 nm at room temperature (20 °C), invariant of salt concentration. The Flory expansion factor (α = Rh(T)/Rh(θ) = 1.5±0.2) was found to be almost constant. θ-Composition for this biopolymer was deduced from turbidimitric titration of aqueous gelatin solutions with the alcohols methanol, ethanol, 2-propanol, and tert-butyl alcohol. It appears that hydrophobic interactions play a crucial role in causing chain collapse at θ-temperature and composition.
UR - http://www.scopus.com/inward/record.url?scp=20144376410&partnerID=8YFLogxK
U2 - 10.1021/bm0492430
DO - 10.1021/bm0492430
M3 - Article
C2 - 15877386
AN - SCOPUS:20144376410
VL - 6
SP - 1623
EP - 1627
JO - Biomacromolecules
JF - Biomacromolecules
SN - 1525-7797
IS - 3
ER -