Dipropargyl ether bisphenol A based boron-containing polymer: synthesis, characterization and molecular dynamics simulations of the resulting pyrolysis and carbonization

Boron-containing polymers have recently attracted worldwide attention due to their ability to affect the thermal and oxidation resistance of an in situ formed material during pyrolytic carbonization. In this work, a novel dipropargyl ether bisphenol A based boron-containing (PB) precursor polymer, which can thermally cure via propargyl groups, was synthesized. PB was characterized with Fourier transform infrared spectroscopy and nuclear magnetic resonance (H-1, B-11 and C-13). Thermogravimetric analysis indicated the outstanding thermo-oxidative stability of PB thermosets with the temperature of 5% weight loss of 362 degrees C and char yield of 56.7% at 800 degrees C in air, while those are 416 degrees C and 74.0%, respectively, in nitrogen. The time evolution of major pyrolysis products including pyrolysis mechanism of PB thermosets were examined via thermogravimetry-Fourier transform infrared spectra as well as reactive molecular dynamics (ReaxFF-MD) simulations. In addition, the carbonized structure of PB thermosets was analyzed using X-ray photoelectron spectroscopy and X-ray powder diffraction. Formation of the graphitic fragment was simulated with ReaxFF-MD. Combining the ReaxFF-MD simulation with the experimental analysis, the way that boron atoms insert into the graphitic structure was illustrated.