ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 39, Number 8
JKCSEZ 39(8)
April 20, 1995 

The conformational properties of poly(ethylene oxide) (PEO) in aqueous solutions are studied by viscometry with respect to the water structure perturbing capabilities of a series of urea solutes at 16℃, and experiments for the effect of amounts of urea and methylurea on PEO at 16 and 25℃ are also performed. The results show that the chain expansion, by ureas, of PEO of 1.0×10⁵ molecular weight at 16℃ is similar to that of PEO of 8.0×10³ molecular weight at 25℃ with respect to the water structure perturbation. Urea and methylurea make the PEO chain expand by the perturbation of water structure around PEO and by the hydrophobic interaction between methylurea and PEO, respectively. PEO of 1.0×10⁵ molecular weight has hydrophobic sites on it, which are roughly classified into two parts; one is the inner hydrophobic groups which can interact between themselves (intramolecular hydrophobic interaction) and prevails at 16℃, and the other is the outer, exposed hydrophobic groups which can interact with the added hydrophobic solute (intermolecular hydrophobic interaction) and prevails at 25℃.