Polymerization of Epoxide with N-(Pyridyl)benzamides as Thermal Latent Anionic Initiators

抄録

A series of N-(pyridyl)benzamides were synthesized from 4-aminopyridine (4AP) by acylation of its amino group with p-substituted benzoyl chlorides and used as novel initiators for polymerization of diglycidyl ether of bisphenol A (DGEBA). Heat evolution by the polymerization was evaluated by differential scanning calorimetry (DSC). The resulting DSC profiles indicated exothermic peaks, of which peak top temperatures were 143－154℃, which was 20℃ higher than that observed for the polymerization using pristine 4AP as an initiator. The initiation activities of these benzamides were controlled by the character of substituent on the benzene ring. It is supposed that the electron density on the nitrogen atom of amide bond affected the reaction temperature. A good correlation was obtained between the DSC peak top temperatures and Hammett constants of the substituents on the benzene ring. The DSC peak top temperature became higher as the substituent group became electron-withdrawing. The initiating mechanism would involve nucleophilic attack of the nitrogen atom in the pyridyl group in the benzamides to epoxide.