Multifunctional electrospun polyamide 6/ochre/carbon black nanofibers for UV protection, flame retardancy, and photothermal antibacterial applications

Abstract

This study explores the synthesis and characterization of low-cost multifunctional nanofibers incorporating ochre (Och) and carbon black (CB) nanoparticles. Och nanoparticles were produced from microparticles via ball milling. EDS analysis identified elemental components such as Mg, Al, Fe, Si, K, and Ti, while XRD confirmed the presence of quartz, Fe₂O₃, and Fe₃O₄ on the Och nanoparticles. Composite nanofibers were fabricated via electrospinning using polyamide 6 (PA6) blended with Och and CB nanoparticles. FESEM analysis revealed that the average diameter of PA6 nanofibers was 133 ± 18 nm, increasing to 149 ± 22 nm for PA6/Och and 159 ± 35 nm for PA6/CB. Analyzing the surface structure of the fabricated nanofibers showed that PA6/Och, PA6/CB, and PA6/Och/CB nanofibers exhibited larger diameters than the PA6 nanofiber sample. Increasing the Och content in the nanofibers enhanced their magnetic absorption properties. The addition of Och and CB nanoparticles to the low-cost multifunctional nanofibers significantly reduced UV transmission, with the lowest transmission observed in the PA6/Och/CB sample. Additionally, the ultraviolet protection factor (UPF) increased significantly with the addition of ochre and CB nanoparticles to the electrospinning solution, rising from 11 to 262, 353, and 561 for PA6, PA6/Och, PA6/CB, and PA6/Och/CB, respectively. The PA6/Och/CB sample also demonstrated an enhanced photothermal response, reaching a temperature of 63 °C under an intensity of 650 mW cm⁻². After 8 seconds, PA6/Och/CB, PA6/Och, PA6/CB, and PA6 exhibited the highest flame-retardant properties in order. The burning lengths for PA6/CB and PA6/Och were measured as 3 cm and 1 cm, respectively, while PA6 was completely destroyed. Notably, the PA6/Och/CB composite exhibited the highest flame resistance, with the shortest burning length among all samples. The PA6/Och/CB multifunctional nanofibers demonstrated excellent photothermal antibacterial performances of 97.89% and 99.97% against S. aureus and E. coli, respectively. The results show that the PA6/Och/CB composite nanofibers with great UPF, flame retardancy, and photothermal antibacterial performances are highly promising for use in advanced multifunctional applications.