Influence of Molecular Weight of Polyethylene Glycol on Interaction between Polyethylene Glycol and Iodine

Interaction of iodine with ethylene glycol, diethylene glycol, triethylene glycol and polyethyleneglycols (PEGs) of molecular weight between 2×102 and 1.1×104 in ethanol and in carbon tetrachloride was investigated. Absorbance of an ethanol solution of iodine at 360nm increased by the addition of PEGs. A new peak was observed at 380 nm by the addition of PEGs of molecular weight above 3×102 to the carbon tetrachloride solution of iodine. These findings were considered to be due to formation of iodine in the diatomic state whose interatomic distance was a little prolonged by the interaction between iodine and PEGs. Formation of iodine in the diatomic state whose interatomic distance was a little prolonged was remarkable when the molecular weight of PEG was high and the concentration of PEG was large. It was considered that the interaction force was a very weak "short-range force." From the results of the measurement of solubility of PEGs in carbon tetrachloride, optical rotatory dispersion spectra and viscosities of the solutions of PEGs, it was suggested that a PEG molecule was in spherical conformation in ethanol and that formation of iodine in the diatomic state whose interatomic distance was a little prolonged might be remarkable in the presence of PEG molecules in spherical conformation.