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<p>In this work, three various chalcone derivatives were prepared: monohydoxylated chalcone, dihydroxylated chalcone, and chloro-hydroxylated chalcone. These chalcones were reacted with the long-chain aliphatic amine of stearyl amine and paraformaldehyde in molar ratios of 1:1:2 by the Mannich condensation reaction to afford three novel benzoxazine monomers. The reaction was carried out by the solution method with a co-solvent of toluene/ethanol at a ratio of 1:1 (V/V). The structures of benzoxazine monomers were confirmed by <sup>1</sup>H NMR and FTIR. To obtain polybenzoxazines, a curing process was performed with a thermal way to complete the polymerization by ring opening process of the oxazine ring. The prepared polybenzoxazines were analyzed by FTIR, while the thermal properties were investigated by DSC and TGA. From the results, it was observed that the structure and the functional groups of benzoxazines had a significant effect on the different properties of the resulting thermosets, such as char yield, curing temperature, and thermal stability. Also, the presence of chalcone moieties in the structure of benzoxazines had a catalytic effect that can lower the temperatures needed for curing. The resulting thermosets have lower curing temperatures ranging from 131&#xa0;°C to 165&#xa0;°C. In addition, they have good thermal stabilities due to the increasing of hydrogen bonding sites and crosslinking density into the polybenzoxazine chains.</p>

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Synthesis, characterization, and thermal properties of different chalcone-based polybenzoxazines

  • 期刊论文

  • 发表日期：

    2026年6月24日

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  • Hamada S. A. Mandour,
  • Ahmed Rehab,
  • Mohamed Elnahrawy,
  • Nehal Salahuddin

摘要

In this work, three various chalcone derivatives were prepared: monohydoxylated chalcone, dihydroxylated chalcone, and chloro-hydroxylated chalcone. These chalcones were reacted with the long-chain aliphatic amine of stearyl amine and paraformaldehyde in molar ratios of 1:1:2 by the Mannich condensation reaction to afford three novel benzoxazine monomers. The reaction was carried out by the solution method with a co-solvent of toluene/ethanol at a ratio of 1:1 (V/V). The structures of benzoxazine monomers were confirmed by 1H NMR and FTIR. To obtain polybenzoxazines, a curing process was performed with a thermal way to complete the polymerization by ring opening process of the oxazine ring. The prepared polybenzoxazines were analyzed by FTIR, while the thermal properties were investigated by DSC and TGA. From the results, it was observed that the structure and the functional groups of benzoxazines had a significant effect on the different properties of the resulting thermosets, such as char yield, curing temperature, and thermal stability. Also, the presence of chalcone moieties in the structure of benzoxazines had a catalytic effect that can lower the temperatures needed for curing. The resulting thermosets have lower curing temperatures ranging from 131 °C to 165 °C. In addition, they have good thermal stabilities due to the increasing of hydrogen bonding sites and crosslinking density into the polybenzoxazine chains.