Two novel macromolecular hindered phenol antioxidants containing thioether and urethane groups, GM-ME-IPDI and GM-ME-TDI, were synthesized successfully by a combination of thiolacrylate Michael addition and nucleophilic addition. The urethane group could function as an antioxidative group, and the urethane group connected with benzene ring had better antioxidative ability than the urethane group connected with alicyclic ring. The antioxidative efficiency of GM-ME-IPDI and GM-ME-TDI were superior to corresponding low molecular weight antioxidant, especially the GM-ME-TDI. The longer the aging time, the more obvious the superiority. In addition, their thermal stabilities were improved obviously, and the thioester could make a considerable contribution
to the thermal stability. Combined with the excellent antioxidative ability and the high molecular weight which endows with good migration resistance, macromolecular hindered phenol antioxidant containing thioether and urethane groups will has a wide application as an antioxidant.