Incorporation of fluorescent quantum dots for 3D printing and additive manufacturing applications

In line with the rapid adoption of 3D printing in both industrial and academic fields, the development of functional materials compatible with 3D printing applications represents a promising direction for the continued advancement and adoption of additive manufacturing technologies. Through various materials processing and design considerations, we demonstrate the ability to incorporate cadmium sulfur selenide graded alloy quantum dots (CdSSe QDs) directly within a polylactic acid (PLA) host matrix to obtain nanofunctionalized, fluorescent filament compatible with stock 3D printing systems. Absorbance, photoluminescence, thermal analysis and mechanical testing are studied to quantify how filament functionalization modulates the optical and material properties of the embedded quantum dots and PLA host matrix following printing. With increasing concentration of embedded quantum dots, a spectral red shift of up to 32 nm relative to CdSSe QDs in solution was observed for 3D-printed PLA/CdSSe QD samples, with the recorded photoluminescence intensity reaching a maximum near a 3%-by-weight loading of CdSSe QDs. Furthermore, the presence of CdSSe QDs within the PLA host matrix was found to influence both the thermal and mechanical response of 3D-printed PLA/CdSSe QD systems. The glass transition temperature was found to decrease by 8 °C relative to the unmodified pure PLA host matrix, while ultimate tensile strength decreased by 64% for the highest concentration of CdSSe QDs in PLA tested. We attribute these deviations in material properties to a combination of interactions between the natively bound surface ligands present on CdSSe QDs and PLA host matrix, and quantum dot aggregation in the final 3D-printed structures. Following materials characterization, we demonstrate the ability to 3D print light pipes based on the optical response of embedded CdSSe QDs, where the overall efficiency and performance was found to be dependent on both the physical light pipe dimensions and concentration of embedded quantum dots.