Abstract
The fundamental properties of polyoxyethylene dodecyl ether (PODE) with different polyoxyethylene chain-lengths (p) have been studied over a wide range of p values. The molecular weights of the PODE, purified by the extraction method using water-saturated n-butanol and n-butanol-saturated water, have been determined by both the freezing point depressions of benzene solutions and the hydroxyl values of PODE; the molecular weights as determined by the different methods are in nearly complete agreement with each other. The Rf-values of the original samples containing small amounts of PEG are slightly lower than those of the purified samples, and the PEG contained in original samples show an almost constant Rf-value, irrespective of the p value. The infrared spectra of purified PODE have been compared with those of the original ones. The spectra of the purified PODE with p-values smaller than about 16 exhibited a carbonyl absorption at 1725 cm−1. However, the reason for this could be established only partially. The effect of the carbonyl group found in the above PODE on the surface tension of aqueous solutions was not observed distinctly. The solubilization behavior of PODE differs somewhat from the behavior of ordinary ionic surfactants, and some solubilization can take place in the region of the surfactant concentration which is lower than the CMC. There appears to be a simple relationship between the CMC values, obtained from solubilization vs. concentration curves, and the p values of PODE over a wide range of p values.

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