Durably and intrinsically antibacterial polyamide 6 (PA6) via backbone end-capping with high temperature-resistant imidazolium

The antibacterial polyamide 6 (PA6) material has attracted great research interest due to its wide application in food packaging, biomedical fields, functional textiles, and other fields. However, it is still a challenge to prepare intrinsically antibacterial PA6 with highly efficient and durably antibacterial activity via polymerization. Herein, the antibacterial imidazolium ionic liquid of 3-carboxymethyl-1-decyl imidazole chloride was designed and synthesized for adapting the polymerization and processing temperature of PA6. Then antibacterial PA6 (PA6-IL) was synthesized through hydrolyzed ring-opening copolymerization with imidazolium at the end of the backbones. Compared to physical blending or post-modification methods, antibacterial agents as end-capping reagents of polymer backbones endowed PA6 with intrinsic antibacterial activity. As expected, the obtained PA6-IL exhibited not just comparable physicochemical and mechanical properties to conventional PA6 but excellent antibacterial activity of low antibacterial time to 60 min and durability for 28 days. Additionally, the corresponding electrospun PA6-IL nanofibrous membranes showed homogenous morphology and remarkable hydrophilicity of 7.7° as well as the high-efficient antibacterial activity. Melt-spun PA6-IL microfibers revealed a smooth surface as well as enhanced tensile strength and increased breaking elongation compared to those of conventional PA6. The PA6-IL microfibers also behaved with excellent antibacterial efficiency and durability. Accordingly, this work provides a feasible and straightforward strategy to prepare durably and intrinsically antibacterial PA6 materials especially PA6 fibers, which can be widely applied in the textiles field.