Automated, Continuous Flow Reactor for the Mass Production of Photoluminescent Nanoparticles E. Simsek, O. V. Akgun, E. Heves, L. Dogan, I. Hocaoglu, P. Dagtepe, N. Sezen and H. T. Ruzgar Kuantag Nanoteknolojiler Gelistirme ve Uretim A. S., Istanbul, Turkey, eren.simsek@kuantag.com ABSTRACT We demonstrate a fully automated, continuous flow process design for the mass production of photoluminescent nanoparticles. The design comprises advanced glass reactors which not only provide good mixing and good heat transfer during the entire reaction interval, but also allow on-line spectroscopic characterization from the radiation transparent reactor surface, without intruding into the reaction media. In addition to these unique features, the process possesses state of the art properties of recent flow reactor designs such as consecutive production line segments on which different reaction parameters can be applied. All the monitoring equipment, pumps, valves, thermostats, and etc. are computer controlled, so that, the characterization data can be used effectively to self- optimize the final product properties in an automated fashion. Keywords: flow reactor, photoluminescent nanoparticle, quantum dot, automation 1 INTRODUCTION Batch and flow reactors are two most common production methods employed widely in various chemical industries. The main advantage of flow reaction systems over batch reactors is the continuous production capability. Besides, particularly for the production of fine chemicals where efficient mass and heat transfer is crucial for homogenous reaction kinetics, flow reactor channels offer much to improve product quality without altering the production capacity in comparison to bulky batch systems. As an example to fine chemicals production, nanoparticle synthesis require good reaction kinetics control since small differences in elemental composition and particle geometry may have drastic effects on overall product properties. Accordingly, in the past 15 years, a number of efforts has been showed for developing flow reactor technologies which are suitable for mass production of nanoparticles with a feasible “scaling up without drawbacks in the product quality” perspective. Flow reactors also offer various flexibilities for better process designs. One of the popular applications is separating the production line into different reaction segments, for instance, employing different heating regions for particle nucleation, growth and shell/coating addition step for a core/shell nanoparticle, a quenching step for stabilizing the final particles, and etc. To control the final product quality, spectroscopic characterization is required during or after each reaction step so that appropriate actions can be taken accordingly. Most of the time, employment of flow cells are required for this purpose since the polymeric or metal tubings used widely as reaction platforms in conventional flow reactors are either opaque or slightly transparent for in-line spectroscopic characterization. These flow cells are likely to lead to formation of dead volumes in the production line and have the risk of introducing regular product contaminations and quality control problems. To overcome these drawbacks, we have developed a process that makes use of glass reaction modules which are radiation transparent, and also have non-linear channel geometries which provide good mixing and good heat transfer during the entire reaction interval. 2 THE PRODUCTION PROCESS 2.1 Precursor System Most nanoparticle productions comprise the reaction of precursors, which possess the main particle forming elements. The precursors, whether formed by a simple dissolution in the solvent, or after a chemical reaction such as complex formation with ligands, require a preparation step performed – most of the time – under inert atmosphere, before dosing into the flow reactor. To maintain the continuity of the production, we use a two heated-stirred vessel system, one is employed as a batch reactor for the preparation of the precursors and the other functions as a tank from which the precursors are pumped into the reactor. Vessels are connected to each other with a transfer pump, so that ready-to-use precursor can be transferred into the tank under inert atmosphere to maintain a minimum precursor level and used readily for the production. Accordingly, precursor preparation and dosing to the reactor can be performed simultaneously, without halting the continuous production. 2.2 Flow Reactor For the production of fine nanoparticles having narrow particle size distribution, fast nucleation followed by a slower growth might be necessary, in most cases. From a quantity point of view, the completion of these reaction intervals must be sufficiently fast to provide a high production capacity for a kinetically fixed residence time in a mechanically fixed reactor volume (basically, flow rate equals reactor volume divided by residence time). From a Advanced Manufacturing, Electronics and Microsystems: TechConnect Briefs 2016 1