Solution behavior of a surfactant aldehyde - the oxidation product of an alcohol ethoxylate

It has previously been shown that alcohol ethoxylates readily undergo autox idation and that one of the major oxidation products is the surfactant alde hyde, i.e. an ethoxylate carrying a -CH2CHO group at the terminal end of th e polyoxyethylene chain. In this work the cloud point, phase behavior and a ggregation characteristics of the surfactant aldehyde produced by oxidation of C12H25(OCH2CH2)(5)OH (C12E5) are determined and compared with the value s obtained with the parent surfactant. It was found that the physico-chemic al behavior of the two species was very similar, which indicates that a con siderable portion of the aldehyde group is in hydrated state, i.e. the surf actant aldehyde consists of a mixture of aldehyde in carbonyl form and the corresponding geminal diol. The cloud point of the surfactant aldehyde decr eased rapidly with time, even when it was stored at low temperature. Also t he parent surfactant and its homologue C12E6 exhibited a decrease in cloud point during storage. For instance, a 1% aqueous solution of C12E6 showed a cloud point decrease from 62 to 32 degrees C after 4 months storage at 40 degrees C. Such a change in solution behavior can have important practical implications. (C) 1999 Elsevier Science B.V. All rights reserved.