Impact of Ring‐Closed Ratio on Properties of Benzoxazine via Solvent‐Free Continuous Flow Synthesis

Abstract A solvent‐free benzoxazine (Bz) synthesis process was established using continuous flow, utilizing p‐ cresol, n ‐butylamine, and an aqueous formaldehyde solution as raw materials to prepare Bz monomer of C‐ba. The optimization of process parameters resulted in a p‐ cresol conversion of 93.5 % ± 1.1 %, a yield of 86.9 % ± 0.8 %, and a ring‐closed ratio (RCR) of 90.0 % ± 1.0 % under optimal conditions. The continuous flow process not only enhanced the RCR from 88.1 % to 90.0 % but also significantly reduced the reaction time by 96.7 % compared to traditional batch processes. Additionally, C‐ba with varying RCR values were investigated for their thermal properties, hydrophobicity, and antibacterial performance.