Medical grade polyamide 12 silver nanoparticle filaments fabricated with in-situ reactive reduction melt-extrusion: rheological, thermomechanical, and bactericidal performance in MEX 3D printing

Abstract

The development of bioactive, multi-functional, and cost-effective nanocomposite filaments for additive manufacturing (AM) is pivotal for the evolution of biomedical and healthcare sectors. Herein, an industrially scalable process is reported, to produce medical grade PA12/AgNP nanocomposites, through in-situ reactive melt-mixing, occurring within the filament extruder. Bactericidal elemental nanoparticles (Ag0) were formed by silver ions (Ag+) reducing from the Silver Nitrate (Ag2NO3) precursor, which was suitably added to the polymer melt. Polyvinyl Alcohol (PVA) was deployed in the compound melt, as a reducing macromolecular agent. The produced nanocomposite filaments were utilized to fabricate samples with Material Extrusion (MEX) AM. A total of sixteen (16) different tests were conducted on filaments and 3D-printed samples to assess their mechanical, rheological, thermal, and antibacterial characteristics, in accordance with international standards. The nanocomposites exhibited a significant mechanical reinforcement of up to 50% compared to PA12. Additionally, the Ag-based nanocomposites demonstrated remarkable antimicrobial behavior in the presence of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) microbes.