Microfluidic investigation of gynamical surfactant rearrangement at the water/oil interface during single droplet formation

单液滴形成过程中水/油界面处运动表面活性剂重排的微流控研究

• 批准号: 1915135
• 金额: --
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1915135
• 关键词: Microfluidic; investigation; gynamical; surfactant; rearrangement

The transport of complex fluids and multiphase flows such as colloidal suspensions, polymers or emulsions is a common feature of natural as well as industrial processes at all length scales. By exploiting laminar flow conditions typical of microfluidics, it is possible to achieve precise control over a range of flow characteristics. One major benefit of microfluidic is the possibility to investigate the formation of emulsions by studying the dynamics of formation of each single droplet. In particular, during droplet formation, a new interface is formed rapidly. The stability of the emulsion is guaranteed by the presence of surfactants. Depending on the relative size and affinity with the system, the surfactant molecules can migrate towards the new interface faster or slower than the speed at which the interface itself is created [Kovalchuk, Nowak, Simmons, Langmuir, 32(20):5069-77, 2016], although no microscopic study has been performed so far. The investigation of this phenomenon is fascinating and the implications are extremely interesting and important for both industrial and fundamental science reasons.One of the expected outputs of this PhD project will be the experimental study of the formation of a single droplet in a two-phase system (either water in oil or oil in water) in the presence of different surfactants by means of advanced optical techniques. In particular, we will design and realize different microfluidic devices, and we will extensively use optical microscopy and fast camera recordings (up to 50,000 frames per second) in order to evaluate differences in the behaviour of the interface between dispersed and continuous phase. The velocity field will be analysed with an innovative technique called Ghost Particle Velocimetry [Buzzaccaro et al., Phys. Rev. Lett., 111, 2013; Pirbodaghi, Vigolo et al., Lab Chip, 15, 2015].It will also be required to perform a fundamental study on the generation of emulsions in microfluidic and the computational modelling of the fluid dynamics of the single droplet formation inside the microfluidic device.

输送复杂的流体和多相流，如胶体悬浮液、聚合物或乳状液，是所有长度范围的自然和工业过程的共同特征。通过利用微流体典型的层流条件，可以实现对一系列流动特性的精确控制。微流控技术的一个主要优点是可以通过研究每个液滴的形成动力学来研究乳状液的形成。特别是，在液滴形成过程中，迅速形成了新的界面。表面活性剂的存在保证了乳状液的稳定性。根据相对大小和与体系的亲和力，表面活性剂分子向新界面迁移的速度可以快于界面本身的创建速度，也可以慢于界面本身的创建速度[Kovalchuk，Nowak，Simmons，Langmuir，32(20)：5069-77,2016]，尽管到目前为止还没有进行微观研究。对这一现象的研究是非常有趣的，其意义对于工业和基础科学来说都是非常重要的。本博士项目的预期成果之一将是利用先进的光学技术对两相体系(无论是水在油中还是在油中在水中)在不同表面活性剂存在下形成单个液滴的实验研究。特别是，我们将设计和实现不同的微流体设备，我们将广泛使用光学显微镜和快速摄像机记录(高达每秒50,000帧)，以评估分散相和连续相之间界面行为的差异。速度场将用一种名为幽灵粒子测速的创新技术进行分析[Buzzaccaro等人，Phys.Rev.Lett，111,2013；Pirbodaghi，Vigolo et al.，Lab Chip，15,2015]它还需要对微流体中乳状液的产生和微流体装置内单液滴形成的流体动力学进行基础研究。