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  1. Colloidal semiconductor nanocrystals with tunable optical and electronic properties are opening up exciting opportunities for high-performance optoelectronics, photovoltaics, and bioimaging applications. Identifying the optimal synthesis conditions and screening of synthesis recipes in search of efficient synthesis pathways to obtain nanocrystals with desired optoelectronic properties, however, remains one of the major bottlenecks for accelerated discovery of colloidal nanocrystals. Conventional strategies, often guided by limited understanding of the underlying mechanisms remain expensive in both time and resources, thus significantly impeding the overall discovery process. In response, an autonomous experimentation platform is presented as a viable approach for accelerated synthesis screening and optimization of colloidal nanocrystals. Using a machine-learning-based predictive synthesis approach, integrated with automated flow reactor and inline spectroscopy, indium phosphide nanocrystals are autonomously synthesized. Their polydispersity for different target absorption wavelengths across the visible spectrum is simultaneously optimized during the autonomous experimentation, while utilizing minimal self-driven experiments (less than 50 experiments within 2 days). Starting with no-prior-knowledge of the synthesis, an ensemble neural network is trained through autonomous experiments to accurately predict the reaction outcome across the entire synthesis parameter space. The predicted parameter space map also provides new nucleation-growth kinetic insights to achieve high monodispersity in size of colloidal nanocrystals.
  2. Aqueous polymer dispersions are commodity materials produced on a multimillion-ton scale annually. Today none of these materials are biodegradable because the process by which they are made is not compatible with the synthesis of biodegradable polymers. Herein, we report a droplet microfluidic encapsulation strategy for protecting a water incompatible ring opening polymerization (ROP) catalyst from the aqueous phase, yielding biodegradable polymer particles dispersed in water. Polymerization yields 300 μm sized particles comprised of biodegradable poly(δ-valerolactone) with molecular weights up to 19.5 kg mol−1. The success of this approach relies on simultaneous precise control of the kinetics of polymerization, the rate of mass transfer, and fluid mechanics. The power of this methodology was demonstrated by the synthesis of cross-linked polymer particles through the copolymerization of bis(εcaprolactone-4-yl)propane and δ-valerolactone, producing cross-linked polymer particles with molecular weights reaching 65.3 kg mol−1. Overall, this encapsulation technique opens the door for the synthesis of biodegradable polymer latex and processable, biodegradable elastomers.