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)/SiOand PEG-DA/Alwith single or multiple vias and the corresponding inorganic particles of SiOand Alsynthesized using the Stop Flow Lithography (SFL) method is reported. Precursor suspensions of PEG-DA, 2-hydroxy-2-methylpropiophenone, and SiOor Alnanoparticles 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 SiOand Alparticles were obtained through polymer burn-off and sintering of the composites. The synthesis of porous inorganic particles of SiOand Alwith 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 SiOparticles and 73-81 m2/g for Alparticles. Surface areas as high as 114 m2/g were measured for multivia cubic SiOparticles. The findings suggest that, with optimization, the particles should have applications in areas where high surface area is important such as catalysis and sieving.