Study on the Ring-Opening Polymerization of Benzoxazine through Multisubstituted Polybenzoxazine Precursors

Abstract

To discuss the mechanism of ring-opening polymerization (ROP) of benzoxazine, a bisphenol A/diaminodiphenylmethane-based polybenzoxazine precursor (PBz-0M), o-dimethylbisphenol A/diaminodiphenylmethane-based polybenzoxazine precursor (PBz-2M), and o-dimethylbisphenol A/o-tetramethyldiaminodiphenylmethane-based polybenzoxazine precursor (PBz-6M) were prepared. Among the polybenzoxazine precursors, free ortho positions to the O of oxazine are available for PBz-0M. No free ortho or para position to the O of oxazine is available for PBz-2M, but free ortho position to the N of oxazine is available. No free ortho positions to the O or N of oxazine are available for PBz-6M. According to DSC, IR, and thermal analysis, we found that the ROP of PBz-2M can be carried out even though no free ortho or para position to the O of oxazine is available. We conclude that the ROP is carried out through the ortho position to the N of oxazine and propose a reaction mechanism to explain the polymerization.

Low melting point, high thermal stable branched benzoxazines resin derived from mixed-substituted phosphazene core

“…The 1 H NMR, 13 C NMR, 31 P NMR and 19 F NMR spectra (DMSO as solvent) of monomer 4m are shown in Figure 2 and the corresponding data of all six monomers are collected in Table 1. Signals (Figure 2a) at 4.60-4.64 ppm (Ar-CH 2 -N) and 5.39-5.43 ppm (O-CH 2 -N) for benzoxazine structure [59] are observed in all monomers. The multiple peaks at 6.63-7.67 ppm are ascribed to the aromatic protons.…”

Synthesis and thermal properties of phenol- and amine-capped main-chain benzoxazine oligomers with multiple methyl substitutions

“…45,46 Lin’s group studied the ROP of MCBP with selectively blocked reactive sites. 47 In this study, with both main-chain and end-capping simultaneously, MCBO is distinctive from benzoxazine monomer and MCBP. As reactive sites exist on both components, the effect of different reactive sites on the polymerization and properties becomes more sophisticated (Figure 2).…”

The Journey of Phenolics from the First Spark to Advanced Materials

“…And, generally, the initiation step involves the protonation of N or O atoms of the oxazine ring and subsequent cleavage of O−CH 2 −N bridge to form cationic species. Then, through electrophilic aromatic substitution, these cations react with the aromatic ring to form Ar−CH 2 −N linkages (Scheme ) …”

“…Then, through electrophilic aromatic substitution, these cations react with the aromatic ring to form ArÀ CH 2 À N linkages (Scheme 11). [68][69][70][71][72] In light of mechanistic studies, it is clear that the initiation step can be catalyzed by cation forming compounds or acids to reduce the curing temperatures. Two major approaches emerged to overcome the high ring-opening polymerization temperatures (T ROP ) of benzoxazine monomers.…”