Effect of hydrophobe structure on performance of alcohol ethoxylates

Alcohol ethoxylates are versatile surfactants because both the hydrophobic and the hydrophilic moieties can be varied readily to change performance. Many studies have focused on the effect of changes in the average length of the hydrophobe and the nature of the hydrophile. Less frequently studied, however, has been the effect on performance of hydrophobe structure, yet this can be varied easily by changing the alcohol feedstock used to make the alcohol ethoxylate. This study compares the performance of alcohol ethoxylates derived from oleochemical alcohol and oxo-alcohols derived from kerosene, butylene, or coal by the Fischer-Tropsch process. Two aspects of hydrophobe structure were found to be important for performance of alcohol ethoxylates: the overall linearity of the parent alcohol and the degree of substitution at the C2 carbon. As the linearity of the parent alcohol increases, the critical micelle concentration (CMC) decreases and the surface tension at the CMC increases. Increasing substitution at the C2 carbon increases the amount of unethoxylated alcohol in the ethoxylate but decreases the inverse cloud point temperature, wetting time, and foam stability in the absence of soil.