A fully automated remote controllable microwave-based synthesis setup for colloidal nanoparticles with integrated absorp
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A fully automated remote controllable microwave-based synthesis setup for colloidal nanoparticles with integrated absorption and photoluminescence online analytics Simon Einwächter 1,2 , Michael Krüger1,2 1 Freiburg Materials Research Centre, University of Freiburg, D-79104 Freiburg, Germany 2 Institute for Microsystems Technology, University of Freiburg, D-79110 Freiburg, Germany ABSTRACT We present a fully automated microwave-based synthesis setup for colloidal nanoparticles. Integrated absorption and photoluminescence online analytics opens the possibility to monitor the growth of various nanoparticles at any stage of the reaction. Spectroscopic investigation within the first seconds of a reaction is accessible opening the possibility to detect potential critical size nuclei as a function of the reaction conditions. Beside the possibility to perform systematic mechanistic studies, this system allows a high degree of synthesis control leading to very good product reproducibility. In conjunction with an automated auto sampler unit systematic multiple reactions can be performed one after each other and compared. The setup is remote-controllable allowing worldwide online control accessibility over the synthesis setup including data processing, visualization and storage. The performance of the setup will be demonstrated by using the synthesis of CdSe nanocrystals as a model system and can be extended to the synthesis of various metallic and semiconducting nanoparticles. INTRODUCTION One major challenge for the synthesis of nanomaterials and nanoparticles is the reproducibility and the up scalability of the synthesis in terms of controlling the size, morphology, surface constitution and crystallinity of the resulting particles which often determines specific chemical and physical properties. In chemical laboratories colloidal nanoparticles are often synthesized via classical routes using standard flasks and equipment such as heaters and stirrers etc. By even using the same synthesis protocol, two different people often achieve different results depending on their individual interpretation of the protocols and differences in physical and chemical parameters influencing the reaction which are usually not described and well documented such as, heating rate, stirring velocity, size of the reaction vessel, chemical impurities etc. Some of the critical parameters for the synthesis of CdSe quantum dots using the manual colloidal hot injection synthesis method are described in Ref. [1]. Microwave based approaches as well as microfluidic reactor based approaches for the synthesis of nanoparticles have been explored for both, improving the control over the reaction for enhancing reproducibility and for up scaling syntheses which is especially important for the development of applications based on nanoparticles and nanoparticle hybrid materials. While microwave based synthesis approaches are usually performed in commercially available instruments the microfluidic approach needs more engineering and designing skills. Strauss and C
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