Development and Optimization of Medical-Grade Multi-Functional Polyamide 12-Cuprous Oxide Nanocomposites with Superior Mechanical and Antibacterial Properties for Cost-Effective 3D Printing

Abstract

In the current study, nanocomposites of medical-grade polyamide 12 (PA12) with incorporated copper (I) oxide (cuprous oxide-Cu2O) were prepared and fully characterized for their mechanical, thermal, and antibacterial properties. The investigation was performed on specimens manufactured by Fused Filament Fabrication (FFF) and aimed to produce multi-purpose geometrically complex nanocomposite materials that could be employed in medical, food, and other sectors. Tensile, flexural, impact and Vickers microhardness measurements were conducted on the 3D-printed specimens. The fractographic inspection was conducted utilizing scanning electron microscopy (SEM), to determine the fracture mechanism and qualitatively evaluate the process. Moreover, the thermal properties were determined by thermogravimetric analysis (D/TGA). Finally, their antibacterial performance was assessed through a screening method of well agar diffusion. The results demonstrate that the overall optimum performance was achieved for the nanocomposites with 2.0 wt.% loading, while 0.5 wt.% to 4.0 wt.% loading was concluded to have discrete improvements of either the mechanical, the thermal, or the antibacterial performance.

Trilateral Multi-Functional Polyamide 12 Nanocomposites with Binary Inclusions for Medical Grade Material Extrusion 3D Printing: The Effect of Titanium Nitride in Mechanical Reinforcement and Copper/Cuprous Oxide as Antibacterial Agents

“…They are used in various engineering applications, such as catalytic applications [ 1 ], films and membranes [ 2 ], food packaging [ 3 ] among other fields, and medical applications [ 4 , 5 ], as they come in medical grades [ 5 ] and composite forms which are suitable for antibacterial activities [ 6 ] and orthopedic applications [ 7 ]. Polyamide 12 (PA12) is a popular polyamide, due to its enhanced thermal and mechanical response [ 8 ]. This specific grade has been investigated and applied in different additive manufacturing (AM) processes, such as binder jetting [ 9 ], powder bed fusion [ 10 , 11 ], and material extrusion (MEX) as pure material, or as the matrix material in composites [ 5 , 8 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ].…”

“…Polyamide 12 (PA12) is a popular polyamide, due to its enhanced thermal and mechanical response [ 8 ]. This specific grade has been investigated and applied in different additive manufacturing (AM) processes, such as binder jetting [ 9 ], powder bed fusion [ 10 , 11 ], and material extrusion (MEX) as pure material, or as the matrix material in composites [ 5 , 8 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. PA12 is a material suitable for the 3D printing (3DP) process, due to its rheological characteristics [ 22 ], its toughness, and high strain values before its failure [ 10 , 23 , 24 , 25 ].…”

“…As a result, nanocomposites for 3DP and AM, in general, have been developed and characterized with improved mechanical, electrical, and thermal properties [ 20 , 33 , 34 ]. At the same time, properties such as antibacterial response have been introduced in biocompatible and medical grade materials, making them suitable for different healthcare and medical applications [ 4 , 5 , 8 , 35 ].…”

“…For the development of composites and nanocomposites with antibacterial properties, additives with such properties are introduced into the materials, with copper (Cu) and its oxides, such as copper (I) oxide (cuprous oxide, Cu 2 O), frequently used in the literature [ 8 , 32 , 34 , 35 ]. Cu in different types (nanopowder and others) has been widely used and investigated in the literature for various types of applications [ 59 , 60 , 61 , 62 ].…”

“…Cuprous oxide has been employed in semiconductors [ 67 , 68 ], among other applications; still, it is mainly used and investigated for its antibacterial properties [ 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 ]. Its antibacterial properties have also been exploited in vat photopolymerization [ 32 , 34 ] and MEX 3DP for polylactic acid (PLA) [ 35 ] and PA12 polymers [ 8 ], achieving sufficient antibacterial performance in the nanocomposites developed in these studies. Copper and other metal nanoparticles (NPs) biocidal properties are achieved, since they have physicochemical characteristics, imitating the host defense peptide (HDP), which is the main mechanism in living organisms for killing or inhibiting bacteria [ 77 , 78 ].…”