微流控-电场协同调控双重微液滴中反应结晶成核过程的机理研究

Crystal nucleation is the most important step in crystallization. The critical of improving product qualities depends on effectively controlling enormous numbers of nuclei in reactive crystallization; The thorny issue for illuminating crystal nucleation mechanism is how to precisely measure and regulate crystal nucleation rate. Effective mixture of reactants is the key to allow reactive crystallization to be controlled and conducted with high precision. In this proposal, the microfluidic-electric field platform will be built. Calcium chloride and sodium carbonate will be chosen as model compound because of their comprehensive fundamental thermodynamic and kinetic data, and dual core double-emulsion droplet will be prepared using microfluidic device to achieve the encapsulation of reactants. To better control the mixture rate, the pressure of film between reactants in the micro-droplet will be adjusted by the electric field, which can overcome the instantaneous nucleation. Furthermore, the diffusion mechanism of two components will be revealed from macro and micro view by experimental study and flow field simulation. Finally, electric field intensity regulation, real-time tracking of mixture and nucleation process will be achieved based on the high speed camera and image process technology. Additionally, the nucleation mathematical model will be established, and the nucleation mechanism in the micro-droplet under microfluidic-electric field will be explored. The results are promising for the enhancement of theoretical basis and methods for measurement and control nucleation rate in reactive crystallization in micro-droplet.

晶体成核是结晶过程中最重要的步骤。如何有效控制反应结晶过程中瞬间大量成核，是提高产品性能的关键；如何准确测量和调控晶体成核速率，是阐明晶体成核机理的难点。反应物混合方式的设计是实现反应结晶精准控制与提高效率的重要手段，其中调控混合速率是关键。本项目拟通过搭建微流控-电场平台，选取基础数据全面的氯化钙和碳酸钠为具体研究对象，构建可控双核双重微液滴，实现对反应物的有效封装；通过电场调节微液滴中反应物界面间膜的压力来调控其混合速率，克服反应结晶中瞬间成核的缺陷，通过实验研究与流场模拟，从宏观与微观层次揭示电场调控双重微液滴中双组分扩散机制；借助高速相机和图像分析技术，实时跟踪反应物混合和成核过程，测量成核速率，建立成核模型，阐明微流控-电场协同调控微液滴中晶体成核机理。本项目有望开拓一种测量和控制微液滴中反应结晶成核速率的新方法，为调控晶体成核提供理论依据和技术支撑。

晶体成核是结晶过程中最重要的步骤。如何有效控制反应结晶过程中瞬间大量成核，是提高产品性能的关键；如何准确测量和调控晶体成核速率，是阐明晶体成核机理的难点。借助过程分析技术对结晶过程中浓度、粒度进行实时在线测量是研究结晶动力学包括成核、生长的关键。本项目以5’-呈味核苷酸二钠为模型物，采用过程分析技术考察了反溶剂/冷却耦合结晶过程中，不同条件对动力学的影响。除此以外，本项目还选取不同模型物考察了分子蒸馏、不同固体形态包括无定形、共晶、凝胶对产品质量的影响。