Ammonium salt catalyzed ring-opening polymerization of 1,3-benzoxazines

The effect of amine HCl salts as catalysts on the ring-opening polymerization (ROP) of simple 1,3-benzoxazines was investigated. The catalyst effects on the structure of the final polymer was examined and compared. The curing process for each salt-benzoxazine mixture was monitored by using Differential Scanning Calorimetry (DSC) and it was found that amine salts cause clear reduction in ROP temperature. As followed by ¹H NMR investigations, the ring-opening of oxazine can take place even at r.t. when suitable solvent is used. Moreover, the analysis gave evidences that amine HCl salts act as nucleophilic catalyst and their efficiency is dependent on ionization ability and solubility of the salts. Thermal stability of the final polymers was also analyzed using Thermal Gravimetric Analysis (TGA).