(521b) Controlled Assembly of Functional Particles Via a Novel Microfluidic Jet Spray Dryer

Generation of monodisperse micro-particles containing (i) pure lactose; (ii) silica nanoparticles (7nm) and lactose; (iii) silica nanoparticles/lactose doped with Eu(III) have been successfully achieved using a novel spray dryer with a uniquely designed microfluidic aerosol nozzle as the monodisperse droplets generator (Figure 1). Here we investigate the impacts of precursor compositions and concentrations, as well as the drying temperature profile on particle size, morphology, and surface element distribution. Distinct morphologies are observed depending on the precursor compositions, ranging from smooth spherical lactose microparticles to the relatively bowl-like shapes for composites containing silica nanoparticles. The formation of such structures is likely to be induced by the presence of the solid nanoparticles altering the viscoelastic property of the droplets that could lead to uneven drying between the different parts of the composites (Figure 2). Post calcination, transmission electron micrographs of Eu(III)/silica nanoparticles/lactose microcomposites confirm the formation of nano-sized Eu₂O₃ homogeneously embedded on the silica shell (Figure 3). Photoluminescence spectra of these particles indicate that enhancement of photoluminescence intensity is directly related to the europium loading, which could be adjusted from the precursor composition (Figure 4). This work demonstrates a scalable dry synthesis route to assemble relatively complex composites with uniform properties, without extensive conjugation or purification steps commonly required in wet chemistry-based processes.