Abstract: Non-volatile antioxidants are prepared from dialkylphenols and selected vinylic monomers which polymerize cationically with acidic Lewis acid or Friedel-Crafts catalyst systems and attach to the phenolic ring. Operative phenolic antioxidants include 2,6-dialkylphenols particularly 2,6-ditertiarybutyl and 2,6-diisopropylphenol. Suitable vinylic monomers include isobutene and styrene. With 2,6-dialkylphenols the polymer chains attach to the 4-position of the phenol. The molecular weight of the chain or tail is controlled to be within about 1000 to 5000 preferably about 2000-3500, for a balance of anti-oxidant activity and immobility in the matrix polymer.