Hydrogen-bonding characteristics and unique ring-opening polymerization behavior ofOrtho-methylol functional benzoxazine

Abstract

Monofunctional benzoxazine with ortho‐methylol functionality has been synthesized and highly purified. The chemical structure of the synthesized monomer has been confirmed by 1H and 13C nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT‐IR) and elemental analysis. One‐dimensional (1D) 1H NMR is used with respect to varied concentration of benzoxazines to study the specific nature of hydrogen bonding in both ortho‐methylol functional benzoxazine and its para counterpart. The polymerization behavior of benzoxazine monomer has been also studied by in situ FT‐IR and differential scanning calorimetry, experimentally supporting the polymerization mechanism of ortho‐methylol functional benzoxazine we proposed before. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3635–3642

Remarkable improvement of thermal stability of main‐chain benzoxazine oligomer by incorporating o‐norbornene as terminal functionality

“…The OH signal could eventually not be seen as applying D 2 O or deuterated alcohols as solvent. The broadening or disappearance of OH signal in some protic solvents is the result of the interaction between the substrate and protic solvent exhibiting acidity . Clearly, more acidic solvents produce higher intermolecular proton deuterium exchange rates.…”

Examining the effect of hydroxyl groups on the thermal properties of polybenzoxazines: using molecular design and Monte Carlo simulation

“…However, intramolecular hydrogen-bonding system is present only in the ortho-isomer. 32 In addition, both condensation reaction between the methylol and phenyl groups, in a manner similar to the traditional phenolic resins, and the usual cationic ringopening polymerization of the oxazine group during thermal treatment of ortho-methylol functional benzoxazine were found to occur. 33 Unlike smart reactions reported for ortho-functional benzoxazines that further undergo structural transformation forming benzoxazole structure at elevated temperatures, only phenolic moieties can be formed for para-isomer upon heating.…”

Modification of Solventless‐Synthesized Benzoxazine Resin by Phthalonitrile Group: An Effective Approach for Enhancing Thermal Stability of Polybenzoxazines

“…The detailed structural information for the synthesized benzoxazines was also studied by 1 Figure 4a, the DSC thermogram of BA-a shows a very sharp endothermic peak at 110.6 °C, suggesting the excellent purity of BA-a. Besides, BA-a shows the onset of the ring-opening polymerization at 241.9 °C with its maximum centered at 256.6 °C.…”

“…Polybenzoxazine is a relatively new class of thermosetting resin attracting interest from both scientific and industrial communities. [1][2][3] As early as in 1944, Holly and Cope discovered the synthesis of benzoxazine by using phenol, formaldehyde, and amines through the Mannich reaction. [4] However, benzoxazine resins in monomeric types have been systematically studied in recent years.…”