Beyond the concepts of nanocomposite and 3D printing: PVA and nanodiamonds for layer-by-layer additive manufacturing

The use of dispersions of poly(vinyl alcohol) PVA and detonation nanodiamond (DND) as novel inks for 3D printing of variously shaped objects using a layer-by-layer additive manufacturing method is reported. In parallel with the nanocomposites preparation, we designed a 3D printing apparatus and settled protocols for the shaping of hybrid materials, choosing PVA-DND inks as a model system to test the performances of the 3D apparatus. Along with material design and preparation, we discuss the main factors influencing the quality of the final printed objects and enlighten the importance of the matching between the chemical/physical properties of the materials to be extruded and the characteristics of the 3D printer. The thermal and mechanical properties of the printed systems have been tested by Differential Scanning Calorimetry and Contact Resonance Atomic Force Microscopy. The analysis of the mechanical properties of the 3D printed objects evidenced, for 0.5%w/w, 1%w and 5%w DND-loaded nanocomposites, values of mean indentation modulus that are 22%, 44% and 200% higher, respectively, than that of the unloaded PVA. The results of the present research, indicate that an appropriate methodology is able to print PVA-DND nanocomposites in well-defined and shaped structures, suitable for a variety of possible applications.