Abstract
Organic substrates such as oils, plastics, rubbers, and lubricants are deteriorated in the presence of atmospheric oxygen. The oxidative deterioration called autoxidation is a radical chain reaction that constantly generates peroxy radicals to transfer the organic substrates to the corresponding hydroperoxides. In this article, new materials and technologies to prevent the autoxidation of the organic substrates developed by the author are reviewed. Since phenolic compounds are inhibitors of radical chain reactions, they possess antioxidant effects. Not all phenolic compounds, however, efficiently prevent the autoxidation. We found that the antioxidant effects of the phenolic compounds are drastically improved by polymerizing them. In addtition, we have developed the easy and low cost methods to control the degree of polymerization of the phenolic oligomers. Phenolic compounds having sulfide group were also prepared and some of them were found to be very strong antioxidants. The phenolic oligomers and the phenolic sulfides possess antimicrobial activities in addition to their antioxidant effects. Since the hydroperoxides are easily decomposed to generate peroxy radicals to initiate the radical chain reaction, their removal from the organic substrates prevents the autoxidation. We found that the hydroperoxides could be removed by mixing the substrates with aqueous solutions of cyclodextrins, since the hydroperoxides selectively formed inclusion complexes with cyclodextrins.
