Stop Flow Lithography Synthesis and Characterization of Structured Microparticles

Abstract

In this study, the synthesis of nonspherical composite particles of poly(ethylene glycol) diacrylate (PEG-DA)/SiO2and PEG-DA/Al2O3with single or multiple vias and the corresponding inorganic particles of SiO2and Al2O3synthesized using the Stop Flow Lithography (SFL) method is reported. Precursor suspensions of PEG-DA, 2-hydroxy-2-methylpropiophenone, and SiO2or Al2O3nanoparticles were prepared. The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process. A patterned photomask with transparent geometric features masks UV light to synthesize the particles. Composite particles with vias were synthesized and corresponding inorganic SiO2and Al2O3particles were obtained through polymer burn-off and sintering of the composites. The synthesis of porous inorganic particles of SiO2and Al2O3with vias and overall dimensions in the range of ~35–90 µm was achieved. BET specific surface area measurements for single via inorganic particles were 56–69 m2/g for SiO2particles and 73–81 m2/g for Al2O3particles. Surface areas as high as 114 m2/g were measured for multivia cubic SiO2particles. The findings suggest that, with optimization, the particles should have applications in areas where high surface area is important such as catalysis and sieving.