A New Polycyclic Naphthoxazine Resin: Facile Synthesis, Characterization, Polymerization and Thermal Properties of Its Corresponding Thermosets.

A novel polycyclic naphthoxazine resin (NSA-thiq) has been synthesized via N,O-acetal forming reaction between o-hydroxyl naphthaldehyde and 1,2,3,4-tetrahydroisoquinoline. The chemical structure of the monomer was investigated and confirmed by 1 H and 13 C NMR, Fourier-transform infrared (FT-IR) spectroscopy, and high-resolution mass spectrometry. Besides, the ring-opening polymerization behaviour similar to ordinary benzoxazine resins was observed by DSC and in situ FT-IR analyses, leading to the formation of the phenolic cross-linked network. Notably, DSC thermograms indicated that the newly obtained polycyclic naphthoxazine resin exhibits much lower polymerization temperatures compared to many other reported benzoxazine or naphthoxazine resins. Moreover, the corresponding polybenzoxazine (poly(NSA-thiq)) showed comparable thermal stability in comparison with thermosets derived from mono-benzoxazine resins. As a consequence of these unique performances, NSA-thiq was applied as a property modifier for a commercialized benzoxazine resin (BA-a). The glass transition temperature of copolymeric thermosets were enhanced without sacrificing too much thermal stability and heat resistance. With this work, we explore another series of naphthoxazine thermosetting resin, which can provide more examples for constructing composites based on thermoset polymers. This article is protected by copyright. All rights reserved.