Exploring Diverse Synthesis Pathways for Copper- and Silica-Based Janus Nanoparticles

Janus nanoparticles (JNPs) synthesis has caught the scientific community’s attention due to their amphiphilic properties and extensive areas of application. In this work, different new copper–silica-based and silica-based JNPs were synthesized using a novel masking methodology and a self-assembly method based on sol–gel procedures, respectively. Moreover, various techniques were used to characterize the developed nanomaterials, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Two types of copper–silica-based Janus nanoparticles were synthesized with a 40 to 70 nm size, while SiO2-based JNPs of around 135 nm were obtained. The duality of different JNPs was confirmed by SEM and by a simple and economical route based on an emulsion stabilization path: analyzing dispersion/aggregation and associated behavior at the immiscible solvent interface. JNPs exhibited an extended residence time over 20 days at an immiscible solvent interface, thereby enhancing the resulting emulsion interface stability. This behavior highlighted their amphiphilic characteristics in comparison to conventional nanoparticles. Consequently, a procedure to determine nanoparticle amphiphilicity could be further standardized.