Miscible macromolecular antioxidants for polyethers

Oxidation reactions are one of the main reasons for the failure of polymeri c materials. Antioxidants, compounds designed to protect against oxidation, must meet three main requirements for success: (1) an efficient antioxidat ive mechanism, (2) compatibility with the oxidizing polymer, and (3) perman ence within the oxidizing polymer. Common antioxidants are low molecular we ight materials that can easily diffuse, leach, or evaporate from the polyme r they are designed to protect. An increase in the molecular weight of the antioxidant not only decreases diffusion and volatility, but also decreases compatibility since most high molecular weight polymers will not mix. Sele ctive sterically hindered phenolics, however, are concurrently antioxidants and "compatibilizers" through hydrogen bond formation. Carefully designed copolymers containing a small percentage of 2,6-diisopropyl-4-vinylphenol w ere found to mix intimately with two readily oxidizing polyethers and to pr otect them against oxidation.