Research on fluoropyridine-based benzoxazine with high thermal stability and excellent flame retardancy for its application in coatings

Abstract

For widespread application, the performance of thermoset resin-benzoxazine must be progressively enhanced. A new fluoropyridine-based benzoxazine (BF-a) with high thermal stability, excellent flame-retardant performance, and a large water contact angle was synthesized using fluoropyridine, aniline, and paraformaldehyde. The chemical structure of the monomer, curing behavior, thermal stability, and flame retardancy were examined carefully. The results indicate that the curing temperature of newly synthesized benzoxazine is 227.9 °C, which is lower than that of benzoxazine derived from bisphenol A. In addition, the thermal stability and flame resistance of poly(BF-a), as measured by 5 % and 10 % weight loss temperatures (Td5 and Td10), char yield at 800 °C (Yc), limiting oxygen index (LOI), peak heat release rate (PHRR), and total heat released (THR), are at 271 ℃, 371 ℃, 69.4 %, 44.2, 7.4 J·(g K)−1 and 3.5 kJ g−1, respectively, which shows its excellent thermal properties and potential as a flame-retardant material. Furthermore, the performances of poly(BF-a) coatings are also demonstrated. Coatings based on poly(BF-a) have a water contact angle, hardness, surface adhesion, interaction energy, and corrosion rate of 123.5°, 6H, 5B, −842.83 kcal·mol−1, and 0.77 mm year−1, respectively, indicating its potential applicability in coatings for harsh environments.