Experimental investigations of the morphology and the morphology formation of levitated single-particles as a model system for reactive and non-reactive spray processes

喷雾聚合是一种较新的聚合物粉末生产方法。在该工艺中，聚合、颗粒成型、形态形成和干燥在一个工艺阶段进行。由于对这些过程的控制是有限的，因此可以实现液滴非接触定位的声悬浮被用作喷雾过程的模型系统。在这种装置中，特别是考虑了液滴和气相之间的相对速度，实现了反应和干燥的可比条件。在第一个资助期间，声学悬浮被证明是一个适当的喷雾过程模型系统。研究了不同反应体系在固定和非固定条件下的形态形成、干燥和反应动力学。这个后续应用的目的是，根据目前获得的结果，观察不同操作参数下几种反应性和非反应性体系中颗粒的形态形成。然后，应该制定适当的相图的形态。最后，为形态学的选择性控制奠定了基础，并进行了实例验证。在此背景下，我们与NIEKEN教授（形态形成建模）和SIMON教授（快速在线图像分析）合作，也考虑了形态的调节。为此，应将视频图像分析与悬浮液滴光学称重相结合，提高对第二干燥阶段颗粒形态的观察能力。例如，通过这种方式，可以监控孔隙度。由于观察到聚合物相组成对第二干燥阶段的形态形成有特殊的影响，因此也计划对第二干燥阶段进行不同的研究。我们计划对这种影响进行量化，并与NIEKEN教授研究组合作将其纳入建模I。随后，乳液聚合作为一种异相体系也将得到进一步的研究。除了温度或单体组成等参数外，乳化剂浓度等因素也会影响反应和干燥动力学以及形貌。为了生产定制的聚合物粉末，需要了解这些因素。为了验证声悬浮模型系统的鲁棒性，在相同条件下，在喷雾塔内进行干燥和聚合。

Spray polymerization is a comparatively new method for the production of polymer powders. In this process, polymerization, particle shaping, morphology formation and drying is carried out in one single process stage. Since the control of these processes is limited, the acoustic levitation, which enables the contactless positioning of droplets, is applied as a model system for spray processes. In this set-up, comparable conditions of reaction and drying are realized, especially by considering the relative velocity between droplet and gas phase. During the first funding period, the acoustic levitation was proven to be an adequate model system for spray processes. The morphology formation, as well as the drying- and reaction kinetics of different reaction systems were investigated under stationary and non-stationary conditions. The aim of this subsequent application is, basing on the up to now obtained results, observing the morphology formation of the particles in several reactive and non-reactive systems depending on different operating parameters. Afterwards, appropriate phase diagrams of the morphology are supposed to be developed. In the end, a basis is supposed to be built up in order to control the morphology selectively and verified exemplarily. In this context, the regulation of morphology is considered as well in cooperation with Prof. NIEKEN (modeling of morphology formation) and Prof. SIMON (fast online- image analysis). For that purpose, the ability of observing the particle morphology during the second drying phase is supposed to be improved by combining the video image analysis with the optical weighing of levitated droplets. In this way, monitoring the porosity, for instance, can be enabled. Different investigations on the second drying phase are planned as well, since it was observed that the polymer phase composition do have a particular influence on the morphology formation during the second drying phase. This influence is planned to be quantified and included in the modeling I cooperation with the research group of Prof. NIEKEN. Subsequently, emulsion polymerization as a heterogenic system is supposed to be investigated as well. Besides the parameters such as temperature or monomer composition, there are factors like the emulsifier concentration which influence the reaction- and drying kinetics as well as the morphology. For the production of tailored polymer powders, the knowledge about these factors is needed. In order to confirm the robustness of the acoustic levitator as a model system, drying processes and polymerizations are supposed to be carried out in a spraying tower under equal conditions.