Synthesis and Polymerization of 2-Alkyl-1,3-benzoxazines

Abstract

Polybenzoxazine has been found to have high heat resistance. Since benzoxazine (BXZ) has a high degree of freedom in molecular design, it is easy to introduce substituents into BXZ. Therefore, many reports have been made on BXZ prepared from phenols and amines with various substituents. However, few BXZs have been reported that have a substituent on the carbon atom of the oxazine ring. The purpose of this study was to synthesize and polymerize several aliphatic aldehyde-derived BXZs and to investigate the thermal properties of those polymers. 2-Alkyl-1,3-BXZs were synthesized using 4-methyl-2-phenylaminomethylphenol (Mannich base) and aliphatic aldehydes as raw materials. When the thermal properties of 2-alkyl-1,3-BXZs and unsubstituted 1,3-BXZ were examined by DSC, it was found that the peak temperature and heat of polymerization of the thermal ring-opening polymerization were significantly reduced by the introduction of alkyl groups into the oxazine ring.