•One-pot one-time, dropwise, and sequential addition syntheses of nanomaterials•Encodes synthetic procedures into reactor using chemical description language χDL•Synthesis of CdSe QDs, [email protected] core-shell NPs, and Pt-Fe3O4 Janus NPs•Simple, reproducible, and accessible reactor for automated synthesis of nanomaterials Nanomaterials exhibit unique properties that are tunable based on morphology and composition. However, commonly used synthesis procedures may lack complete or accurate knowledge, leading to a reproducibility crisis. To address this, we have developed a new approach that encodes synthesis procedures into a single reactor. Our proof-of-concept automation, which does not rely on electronic components, is demonstrated in the one-pot synthesis of quantum dots, core-shell nanoparticles, and Janus nanoparticles. As materials science continues to advance, we anticipate that reactor capabilities can be further expanded by using cost-efficient and environmentally friendly functional materials. This approach offers a simple, reliable, and reproducible method for nanoparticle synthesis, which can be easily adapted to be used by researchers in different fields. Nanomaterials exhibit unique properties that are tunable depending on their morphology and composition. However, widely used methods can fail due to incomplete or assumed knowledge of the synthesis protocol. A digital synthesis method could unambiguously capture the synthesis process, including required hardware, reagent inputs, and process description, thereby increasing accessibility and improving reproducibility. Our method encodes synthetic procedures into single reactors by imprinting synthetic parameters to the reactor’s morphology, which are described using a chemical description language, χDL. This approach is consolidated into three single reactors that automate complex processes such as one-time, dropwise, and sequential addition for the synthesis of eight time-resolved CdSe quantum dots, [email protected] core-shell nanoparticles, and Pt-Fe3O4 Janus nanoparticles, respectively. This method of translating synthetic parameters into physical instances of a reactor enables the automation of nanomaterial synthesis in a simple, reliable, and reproducible manner, making nanomaterials accessible to researchers from various fields on demand. Nanomaterials exhibit unique properties that are tunable depending on their morphology and composition. However, widely used methods can fail due to incomplete or assumed knowledge of the synthesis protocol. A digital synthesis method could unambiguously capture the synthesis process, including required hardware, reagent inputs, and process description, thereby increasing accessibility and improving reproducibility. Our method encodes synthetic procedures into single reactors by imprinting synthetic parameters to the reactor’s morphology, which are described using a chemical description language, χDL. This approach is consolidated into three single reactors that automate complex processes such as one-time, dropwise, and sequential addition for the synthesis of eight time-resolved CdSe quantum dots, [email protected] core-shell nanoparticles, and Pt-Fe3O4 Janus nanoparticles, respectively. This method of translating synthetic parameters into physical instances of a reactor enables the automation of nanomaterial synthesis in a simple, reliable, and reproducible manner, making nanomaterials accessible to researchers from various fields on demand. Nanomaterials, commonly synthesized as a colloidal dispersion, have been utilized in a variety of electro-, opto-magneto-, mechano-, thermal, or chemo-devices,1Kovalenko M.V. Manna L. Cabot A. Hens Z. Talapin D.V. Kagan C.R. Klimov V.I. Rogach A.L. Reiss P. 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Digitizing chemical procedures, on the other hand, allows us to identify ambiguous or missing parameters and replace them with well-defined variables (e.g., room temperature, stirring rapidly, etc.).10Salley D. Keenan G. Grizou J. Sharma A. Martín S. Cronin L. A nanomaterials discovery robot for the Darwinian evolution of shape programmable gold nanoparticles.Nat. Commun. 2020; 11: 2771https://doi.org/10.1038/s41467-020-16501-4Crossref PubMed Scopus (48) Google Scholar,11Epps R.W. Bowen M.S. Volk A.A. Abdel-Latif K. Han S. Reyes K.G. Amassian A. Abolhasani M. Artificial chemist: an autonomous quantum dot synthesis bot.Adv. Mater. 2020; 32: 2001626https://doi.org/10.1002/adma.202001626Crossref PubMed Scopus (129) Google Scholar,12Langner S. Häse F. Perea J.D. Stubhan T. Hauch J. Roch L.M. Heumueller T. Aspuru-Guzik A. Brabec C.J. Beyond ternary OPV: high-throughput experimentation and self-driving laboratories optimize multicomponent systems.Adv. 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Engl. 2018; 57: 16716-16720https://doi.org/10.1002/anie.201810095Crossref Scopus (14) Google Scholar In the latter example, the precursors were compartmentalized and mixed at high temperatures upon manually flipping the reactor in an oven, leading to the discovery of new reactivity. Our hypothesis is that by implementing digitalized chemical procedures and synthetic parameters of nanomaterial synthesis into the physical geometry of self-contained reactors, a one-pot reactor can be produced, increasing accessibility and reproducibility of these materials. Herein, we developed programmable one-pot reactors by translating syntheses protocols into physical descriptions of sealed reactors. The one-pot reactors were manufactured by combining polymeric materials with different thermal properties to separate precursor solutions into different compartments to prevent early or unwanted reactions. The combination of polymers that can endure desired temperatures (e.g., polypropylene [PP] and polyether-ether-ketone [PEEK]) in composite reactors can be continually optimized for digitizing nanomaterials synthesis. This can be achieved by using high-temperature materials (i.e., PEEK) for the reactor body and low-temperature materials (i.e., seals made of polycaprolactone [PCL]) to separate the compartments. The precursor solutions can be pre-loaded into the reactor, which is then placed in a pre-heated oven where the seals break at a programmed temperature to initiate the reaction. This programmed compartmentalization has been incorporated into three reactor designs that can automate complex procedures such as one-time, dropwise, and sequential addition reactions. The utility of this new approach was demonstrated through the synthesis of time-resolved CdSe quantum dots, [email protected] core-shell nanocrystals, and Pt-Fe3O4 Janus nanoparticles. This general method of digitizing traditional nanomaterials synthesis procedures into an enclosed reactor design can unlock chemistry across various research fields and provide inexperienced researchers with safe, low-cost, and reproducible access to on-demand nanomaterials. Highly luminescent nanocrystals, also known as quantum dots (QDs), have been widely used in various applications, from LED20Steckel J.S. Snee P. Coe-Sullivan S. Zimmer J.P. Halpert J.E. Anikeeva P. Kim L.-A. Bulovic V. Bawendi M.G. Color-saturated green-emitting QD-LEDs.Angew. Chem. Int. Ed. Engl. 2006; 45: 5796-5799https://doi.org/10.1002/anie.200600317Crossref Scopus (250) Google Scholar and photovoltaics21Nozik A.J. Beard M.C. Luther J.M. Law M. Ellingson R.J. Johnson J.C. Semiconductor quantum dots and quantum dot arrays and applications of multiple exciton generation to third-generation photovoltaic solar cells.Chem. 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To speed up the reactor design iteration process and overcome the limitations of materials properties in the current manufacturing process, we implemented a lower-temperature (i.e., 130°C) synthesis of CdSe QDs.24Siy J.T. Brauser E.H. Thompson T.K. Bartl M.H. Synthesis of bright CdSe nanocrystals by optimization of low-temperature reaction parameters.J. Mater. Chem. C. 2014; 2: 675-682https://doi.org/10.1039/C3TC32343ACrossref Google Scholar We first identified the basic synthetic steps for CdSe QDs and designed a reactor that meets those requirements. Synthetic procedures can be described in various ways depending on the laboratory setup and/or researchers. To precisely encode the chemical reaction protocols, we recently developed a new approach using a programming language known as the chemical description language (χDL).25Hammer A.J.S. Leonov A.I. Bell N.L. Cronin L. 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For the lower temperature synthesis of CdSe QDs, the vessel was purged and sealed with a silicone septum to allow the reaction to occur in an inert atmosphere. PP, due to its chemical compatibility and thermal stability (up to 130°C), was used as the structural material for the reactor body. During the reaction, three different precursors were mixed at high temperatures; thus, the reactor was designed to contain three chambers (two for reagents and one as the reaction compartment), all separated by a temperature-sensitive seal made of PCL, as shown in Figure 1. The custom-made seal has different thermal properties than PP (m.p. = 63°C, revealed by differential scanning calorimetry [DSC]; see Figure S1), allowing the polymer to soften and eventually fail at high temperatures. Heating the reactionware cartridge to the reaction temperature (130°C) allowed the reagents to drop into the reaction compartment and initiate the reaction. Initially, a disk-shaped seal (Figure 2A) was designed and incorporated into the reactor body during the printing process to separate the precursor solutions. Varying the width of the seal allowed us to control the time when the solutions were mixed in the reaction compartment. The solutions were transferred into the reaction chamber after 10 (ca. 70°C), 15 (ca. 90°C), and 25 min (ca. 130°C) for the 0.5, 1, and 2 mm seals, respectively. Considering the synthesis starts at 130°C, a 2 mm thickness seal provides the appropriate timing for the reagents to be mixed. To use the programmed reactor, the solutions can be pre-loaded into separate reagent chambers through the septa under inert atmosphere (see supplemental information for preparation procedure). The loaded cartridge was placed in a pre-heated oven at 130°C, and aliquots were taken at 1 h intervals with syringes and long needles. The 2 mm disk-shaped seal resulted in irreproducible photoluminescence (PL) emissions for the first QDs formed during the first 2 h of reaction. Figure 2G (yellow square trace) shows differences as large as ±17 nm between batches for the first and second nanocrystals (after 1 and 2 h of reaction, respectively). The differences suggest an uneven breaking of the seal, leading to a continuous addition of precursors into the reaction mixture instead of a one-time addition, generating multiple nucleation stages. To optimize the breaking of the seal, a cone-shaped seal was designed, focusing the pressure point on the middle section of the seal (Figure 2B). The cone-shaped design is based on a carved-in cone with a total height of 4 mm and a 2 mm bottom thickness to maintain the breaking time and temperature. This new seal resulted in more reproducible PL emissions for the second sample of QDs (±6 nm compared with ±17 nm obtained with the disk-shaped design; Figure 2G). However, the first nanocrystal PL still showed significant differences between batches (±14 nm), most likely due to an uneven temperature distribution between the cartridge and seal batches. To analyze the temperature distribution across the reactor and seal during the reaction, computational fluid dynamics (CFD) simulations were performed on the system (Figure S2). A cross-section of the seal region at the time when the reactor body is at 130°C is shown in Figures 2D and 2E. For the disk- and cone-shaped seals, the highest temperature point across the membrane is located toward the outside edge (104°C), while the middle section of the seal has a ΔT ca. 19°C. The temperature difference suggests that even if there is a pressure point in the seal design, the temperature difference is determined solely by a slow heat transfer in PP and PCL. Knowing that the highest temperature is focused on the external edge of the seal, a new shape was designed to locate the pressure point toward the outer edge (slide-shaped design; Figures 2C and 2F). The slide-shaped seal has a total height of 4 mm, with a 2 mm slope of 24°, leading to a bottom thickness of 2 mm. The seals were loaded into the reactionware cartridge, with the breaking point facing toward the wall of the reactor. The new design resulted in PL properties being more reproducible across different reactor batches, minimizing error bars to ca. ± 3 nm (Figure 2G). Consistent results were obtained with three batches of triplicates (i.e., 9 replicates) compared with using glassware (Figure 2H) indicating that with a standard system reducing human input, the QDs are more reproducible. The time-evolution profile of the CdSe nanocrystal (NC) nucleation and growth process was monitored by UV-visible (UV-vis) and fluorescence spectroscopy for each aliquot (0.5 mL) sampled from the reaction mixtures. To analyze the differences between traditional glassware synthesis and the pre-loaded cartridges, optical absorption and PL emission spectra were obtained from precursor injection to further grow at 130°C (Figures 3A and 3B ). When the NCs are at the early stage of formation (<1 h of precursor injection), broadband emission dominates due to the high surface-to-volume ratio. As the NCs grow, the band edge emission becomes the prominent emission, leading to narrower peaks. The absorbance spectra typically show a peak centered at around 412 nm, indicating CdSe magic-size clusters.30Yu K. Hu M.Z. Wang R. Piolet M.L. Frotey M. Zaman M.B. Wu X. Leek D.M. Tao Y. Wilkinson D. Li C. Thermodynamic equilibrium-driven formation of single-sized nanocrystals: reaction media tuning CdSe magic-sized versus regular quantum dots.J. Phys. Chem. C. 2010; 114: 3329-3339https://doi.org/10.1021/jp909310aCrossref Scopus (71) Google Scholar The transition from clusters to NCs is evidenced by a shoulder appearance in the 450 nm region, along with a drastic change in the PL properties. During the initial growth period, only the cluster broad emission was observed (Figures 3A and 1H), while with the appearance of the absorption shoulder, the PL emission peak sharpens (Figures 3A and 3H). The optical properties of the NC continued to redshift for the remainder of the reaction time, suggesting a continuous growth of the CdSe QDs. For example, after 4 h of precursor injection in glassware, the diameter of the particles is 3 nm, while for the NCs generated with the one-pot system, the diameter is 3.4 nm.31Yu W.W. Qu L. Guo W. Peng X. Experimental determination of the extinction coefficient of CdTe, CdSe, and CdS nanocrystals.Chem. Mater. 2003; 15: 2854-2860https://doi.org/10.1021/cm034081kCrossref Scopus (4743) Google Scholar The PL emission peak full-width-half-maximum (FWHM) for the NCs prepared in glassware samples was 57 ± 3 nm, while for PP reactionware, the FWHM was 60 ± 3 nm, with quantum yields of 1.4% and 3.6%, respectively. To expand the synthesis temperature range, a different combination of 3D printing materials was used for the body and seals of the reactor. PEEK is one of the most chemically and temperature-resistant polymers available, with a printing temperature of ca. 400°C and an application temperature of up to 250°C.32Yang C. Tian X. Li D. Cao Y. Zhao F. Shi C. Influence of thermal processing conditions in 3D printing on the crystallinity and mechanical properties of PEEK material.J. Mater. Process. Technol. 2017; 248: 1-7https://doi.org/10.1016/j.jmatprotec.2017.04.027Crossref Scopus (344) Google Scholar Considering these printing conditions, PCL is not suitable to be used as a seal due to the large difference in thermal properties (ΔTm = 340°C); therefore, a different material ID required for the seals. Commercially available PP (PPcomm), which is sold as a copolymer with PP, has a melting point of 138°C, as revealed by DSC (Figure S1). PPcomm shows a decent adhesion property and good thermal compatibility with PEEK during the printing process, sealing the reactor and preventing leaking between the different chambers. This new PEEK/PPcomm (body/seal) reactor combination can perform synthesis at higher temperatures (180°C). As observed in CFD simulations, when the reactor body is at 180°C, the seal temperature is at ca. 140°C (Figure S3). The PEEK/PPcomm reactor was used for the synthesis of CdSe at 180°C, with the solutions pre-loaded into the cartridge using the same techniques as in the PP/PCL reactor. The first drastic difference between the systems (PP/PCL vs. PEEK/PPcomm) is the timescale. While the PP/PCL reaction requires ca. 4 h to grow to 3.2 nm, the PEEK/PP cartridge requires as little as 10 min to grow to the same size. For this reason, to monitor the growing process of the NCs, aliquots were taken in 5 min intervals (Figure 3C). At high temperatures, the reaction is more thermally driven, and thus there is no peak at ca. 412 nm, corresponding to the magic-size clusters. Figure 3C shows how the optical properties of the NCs redshifted continuously during the reaction; for example, after 15 min of growth, the PL emission FWMH is 43 ± 2 nm. At an elevated temperature (180°C), the reaction requires 5 min to reach a size of 2.6 nm compared with 4 h at 130°C. The CdSe core is usually covered by a semiconductor shell with a high-energy band gap (e.g., ZnS, ZnSe, or CdS) to improve the quantum efficiency. Introducing these shells to the surface of the NCs prevents electron-hole recombination caused by surface dangling bonds.33Vasudevan D. Gaddam R.R. Trinchi A. Cole I. Core–shell quantum dots: properties and applications.J. Alloys Compd. 2015; 636: 395-404https://doi.org/10.1016/j.jallcom.2015.02.102Crossref Scopus (212) Google Scholar To add the shell to the NC, most reactions rely on a two-step synthesis, where the shells can form through the addition of precursors to a reaction mixture containing the cores. To avoid homogeneous nucleation, the shell precursors are typically added dropwise. Among the different shells used to coat the CdSe cores, ZnSe is highly desirable as it prevents interfacial misfits that can turn into traps for electrons and holes. To imprint the synthesis of core-shell QDs into the reactor design, the base processes need to be identified (as depicted in Figure 1). First, two different solutions need to be mixed at 190°C, which requires two chambers. A critical step, the dropwise addition, must also be incorporated when adding the shell precursor. To encode this into the blueprint of the reactor, a new design was developed based on the principle of a Soxhlet extractor. In this design, the reagent compartment was connected to a solution reservoir, which was then connected to the reaction compartment via a U-tube siphon (Figures 4A and S5). A PEEK adaptor was added to the end of the siphon tubing to control the rate of addition. Considering that the reaction is carried out at 190°C, PEEK was used due to its thermal resistance, and PP was used as the material for the seal. The final design containing all these features is shown in Figure 4A. To test the rate of addition, a perylene solution was loaded into the reactionware cartridge and was set up in a pre-heated oven at 190°C. Aliquots were sampled every 3 min, with the first sample collected 25 min after the reaction started, showing how the concentration of perylene increases over time (Figure 4B). The sampling was completed once the absorbance values plateaued, matching the concentration of the diluted stock solution (5 mM). Considering the elapsed time between samples and the total volume that was added, the addition rate using a PEEK adaptor of 2 mm is ca. 0.2 mL/min. After determining the rate of addition, the CdSe QD and ZnSe solutions were loaded into the cartridge and then placed in a pre-heated oven at 190°C, and samples were taken every hour to monitor the shell growth. As shown in Figure 4C, the growth of the ZnSe shell on the surface of the CdSe core shell caused a small bathochromic shift of 25 nm in the UV and the PL spectra. The [email protected] nanoparticles prepared with the cartridge showed a standard deviation of 1.5 nm (Table S2), showcasing the reproducibility of the system. Seed-mediated growth is one of the most successful traditional methods used to control the shapes and properties of noble metal NCs due to its reliability and versatility.34Niu W. Zhang L. Xu G. Seed-mediated growth of noble metal nanocrystals: crystal growth and shape control.Nanoscale. 2013; 5: 3172-3181https://doi.org/10.1039/C3NR00219ECrossref Google Scholar This process involves the sequential reduction of different metal precursors to synthesize various nanoparticle morphologies (e.g., Janus, dumbbell, core shell, etc.).35Murphy C.J. Sau T.K. Gole A.M. Orendorff C.J. Gao J. Gou L. Hunyadi S.E. Li T. Anisotropic metal nanoparticles: synthesis, assembly, and optical applications.J. Phys. Chem. 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