Intermolecular Interactions of Two Non-Ionic Surfactants with Water Studied Through Nuclear Magnetic Resonance

Abstract

Through the use of various nuclear magnetic resonance (NMR) spectroscopic experiments we have studied the intermolecular interactions of two non-ionic surfactants with water. For the two surfactants used in these studies a proton NMR peak assignment has been completed. From the spectral assignments there are several different structures that the surfactant forms depending on the water content of the samples. First, we investigated the intermolecular interactions between water and a non-ionic surfactant, CHEM 1260, having an average of five ethoxy groups per alkyl chain (CaE5, where a is the number of alkyl carbons present in the surfactant and E stands for ethoxy). Proton NMR (1H-NMR) has allowed for the identification of several cross-linking structures formed by the surfactant as water content increases. The second part of this research investigated the intermolecular interactions of a non-ionic surfactant, CHEM 29, consisting of seven ethoxy groups and two isopropoxy groups (CaE7P2, where P stands for iospropoxy) and water. Both 1H-NMR and 13C-NMR were employed in this study. In the CHEM 29 study the presence of water in two different chemical environments was not observed as in the CHEM 1260 study, which lead to the idea that CHEM 29 behaves differently than CHEM 1260 in the presence of water.