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

喷雾聚合法是一种较新的聚合物粉末制备方法。在该工艺中，聚合、颗粒成型、形态形成和干燥在一个单一工艺阶段中进行。由于这些过程的控制是有限的，声悬浮，这使得液滴的非接触式定位，被应用作为一个模型系统的喷雾过程。在该装置中，实现了可比较的反应和干燥条件，特别是通过考虑液滴和气相之间的相对速度。在第一个资助期内，声悬浮被证明是一个适当的模型系统的喷涂过程。在静态和非静态条件下研究了不同反应体系的形貌形成、干燥动力学和反应动力学。该后续应用的目的是，基于到目前为止获得的结果，根据不同的操作参数，观察在几种反应性和非反应性系统中颗粒的形态形成。之后，适当的相图的形态应该是发达国家。最后，为有选择地控制形态提供了依据，并进行了实例验证。在这种情况下，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，在第二干燥阶段期间观察颗粒形态的能力应该通过将视频图像分析与悬浮液滴的光学称重相结合来提高。以这种方式，可以实现例如对孔隙率的监测。还计划对第二干燥阶段进行不同的研究，因为观察到聚合物相组成确实对第二干燥阶段期间的形态形成具有特定影响。计划将这种影响量化并纳入与NIEKEN教授研究小组合作的建模I中。随后，乳液聚合作为一个非均相系统应该进行研究。除了温度或单体组成等参数外，还有乳化剂浓度等因素会影响反应和干燥动力学以及形态。为了生产定制的聚合物粉末，需要了解这些因素。为了确认声悬浮器作为模型系统的鲁棒性，干燥过程和聚合过程应该在相同条件下在喷雾塔中进行。

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.