Effect of O radicals on aramid surface treatment: Experimental and molecular insights

Aramid is widely recognized for its effectiveness as a matrix in high-performance composite materials. However, the inert nature of its surface necessitates plasma pretreatment for proper resin immersion. With a particular focus on interactions involving O radicals, this study employs Vacuum Ultra-Violet Photolysis Reactive-species Supply to investigate the interaction mechanisms between aramid and plasma reactive species. The water contact angle serves as an indicator of the degree of surface reactions, demonstrating a clear correlation between its reduction and the concentration of O radicals. Analysis using ATR-FTIR and XPS revealed the depletion of amide groups and the formation of hydroxyl groups during the treatment process. Through reactive molecular dynamics simulations, we identified the specific reaction sites of the amide groups on aramid and quantified the variations in typical reaction products. We also summarized the reaction pathways and confirmed the generation of polar structures, such as N-OH. This study offers valuable theoretical insights for the surface modification of inert polymers and contributes to advancements in industrial plasma technology.