Synthesis of boron-modified phenolic resins and properties as radiation resistant coatings

Radiation-resistant polymer resins and their usage as protective coatings are the largest non-metallic materials served in radiation scenarios. In this study, heat and radiation resistant boron-modified phenolic resin (BPR) was synthesized by alkaline-catalyzed reaction between phenol and formaldehyde (HCHO), and subsequent condensation with boric acid (H 3 BO 3 ). The optimal feeding molar ratio of phenol: HCHO: H 3 BO 3 was found to be 1:1.5:0.35, at which BPR with linear architecture and the highest boron content (11.6%, atomic percentage) was afforded. Thermogravimetric analysis (TGA) suggested that only 15% weight loss was revealed when heated to 400 °C for BPR35, where 35 represents the feeding molar ratio of H 3 BO 3 was 0.35 relative to phenol, demonstrating the excellent thermal stability and dimensional integrity. After thermal curing, the coating films featured superior hardness, adhesion, impact and abrasion resistance, organic solvent tolerant properties, profiting from the densely crosslinking 3D network. The electron beam and γ-ray radiation study showed that BPRs featured excellent anti-aging and radiation resistance without compromise of hardness and adhesion performance. The damage mechanism of BPR35 coatings under radiation conditions were finally proposed to guide the design and preparation of anti-radiation polymers that can be worked under extreme causative environment (e.g. γ-ray radiation).