Recent advances in optical coding, drug delivery, diagnostics, tissue engineering, shear-induced gelation, and functionally engineered rheology crucially depend on microparticles and microfibers with tunable shape, size, and composition. However, scalable manufacturing of the required complex micromaterials remains a long-standing challenge. Here in-air polymerization of liquid jets is demonstrated as a novel platform to produce microparticles and microfibers with tunable size, shape, and composition at high throughput (>100 mL h-1 per nozzle). The polymerization kinetics is quantitatively investigated and modeled as a function of the ink composition, the UV light intensity, and the velocity of the liquid jet, enabling engineering of complex micromaterials in jetting regimes. The size, morphology, and local chemistry of micromaterials are independently controlled, as highlighted by producing micromaterials using 5 different photopolymers as well as multi-material composites. Simultaneous optimization of these control parameters yields rapid fabrication of stimuli-responsive Janus fibers that function as soft actuators. Finally, in-air photopolymerization enables control over the curvature of printed droplets, as highlighted by high-throughput printing of microlenses with tunable focal distance. The combination of rapid processing and tunability in composition and architecture opens a new route toward applications of tailored micromaterials in soft matter, medicine, pharmacy, and optics.
Keywords: in-air photopolymerization; liquid jets; microfibers; microparticles; shape control.
© 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH.