Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 9/14/2009
Publication Date: 4/15/2011
Citation: Cermak, S.C. 2011. Estolides: biobased lubricants. In: Biresaw G., Mittal K.L., editors. Surfactants in Tribology. Vol 2. Boca Raton, FL: Taylor & Francis. p. 269-320. Interpretive Summary: An overview of the estolide technology developed by an NCAUR scientist is given in this book chapter. Our goal was to synthesize a class of new lubricant compounds that would have better physical properties than normal vegetable oil. Estolides were developed, characterized, and tested in wide range of lubrication and cold weather applications, and experimental approaches were also explained. This book chapter will allow industry and academic researchers to become more familiar with ARS research into finding new uses for vegetable oils.
Technical Abstract: Estolides were originally developed as a cost effective derivative from vegetable oil sources to overcome the problems associated with standard vegetable oils as lubricants. Classic estolides are formed by the formation of a carbocation at the site of unsaturation that can undergo nucleophilic addition by another fatty acid, with or without carbocation migration along the length of the chain, to form an ester linkage. The secondary ester linkages of the estolide are more resistant to hydrolysis than those of triglycerides, and the unique structure of the estolide results in materials that have far superior physical properties for lubricant applications than vegetable and mineral oils. A second type of estolide from lesquerella and castor triglycerides is called triglyceride (TG) estolides. TG estolides have also been developed directly from the triglyceride of the vegetable oil. The TG estolide synthesis utilizes the hydroxyl group already on the molecule for a simple esterification process to form these new estolides. The unique structures of these TG estolides allow for the materials that have far superior physical properties for lubricant applications than vegetable and mineral oils.