Highly Thermally Stable Quinoline-Based Benzoxazine-Modified Epoxy Coatings for Multifunctional Textile Protection

Quinoline-based benzoxazine (QBZ) was synthesized and copolymerized with epoxy resin to develop highly thermally stable, multifunctional thermosetting coatings for textile fabrics with enhanced UV shielding, hydrophobicity, tensile performance, and antibacterial activity. The molecular structure of the synthesized QBZ was confirmed by NMR, FTIR, and HRMS, while DSC and TGA were performed to investigate its curing behavior and thermal stability. The QBZ exhibited an exothermic peak with an onset temperature of 205 °C and a maximum temperature of 219 °C, indicating a relatively low polymerization temperature. The resulting Poly(QBZ) exhibited high decomposition temperatures (T d5 % and T d10 %) of 389 and 449 °C, respectively. Moreover, it exhibited a high char yield of 77 % at 800 °C, confirming its excellent thermal stability. For the modification of epoxy-coated textile fabrics, QBZ/epoxy copolymer coatings with weight ratios of 25/75, 50/50, and 75/25 were investigated. Increasing the QBZ content progressively enhanced the UV-shielding and water-repellent properties of the coated fabrics. In particular, Copolymer 3 (75/25 wt%) exhibited the highest water contact angle of approximately 128° and the highest initial UPF values of 74.91 and 76.51 for UV (B, C) and UV(A), respectively, which remained high after 30 washing cycles. In contrast, Copolymer 1 (25/75 wt%) provided the best mechanical and antibacterial behavior, reaching a tensile strength of approximately 52.7 MPa and achieving complete bacterial elimination of S. aureus together with a 3.2-log (99.9%) reduction against E . coli . Overall, the new copolymer system provides a versatile multifunctional coating platform capable of simultaneously imparting UV shielding, hydrophobicity, mechanical reinforcement, and antibacterial functionality to textile fabrics.