SURFACE TENSION AND SELECTED MICELLAR SOLUTION THERMODYNAMIC PROPERTIES OF SOME N,N-BIS-(2-HYDR0XYETHYL) AMIDES

ABSTRACT

Several surface tension and micellar solution thermodynamic properties of some N,N-bis-(2-hydroxyethyl) amides have been determined and compared with those of other nonionic surfactants. The ADEA's, which have never before been investigated, were found to have properties quite similar to those of other nonionics. The values obtained agree well with those of other nonionic surfactants of similar hydrophobe chain length. The effect of temperature on these properties is much less for the ADEA's than for ethyoxylated surfactants.

The effect of hydrophobe branching was examined and found to be of minor consequence compared to the influence of total chain length. Among isomers of the same total chain length, the maximum surface activity (as measured by the extent of adsorption at the air-solution interface) is obtained not with a normal- or mid-chain branched compound but with the 2-C_n isomer.

The ADEA's are unusual in their pattern of effectiveness of surface tension reduction. For most surfactant efficiency increases but effectiveness decreases with increasing chain length. For ADEA's, the most efficient compounds tend to be the most effective as well. ADEA's appear to be unique in their ability to lower surface tension extremely efficiently yet very effectively.