Synergizing Surfactants and Electric Fields to Engineer the Mechanics of Fluid-Fluid Interface.

协同表面活性剂和电场来设计流体-流体界面的力学。

• 批准号: 1804548
• 负责人: Lynn Walker
• 金额: $ 38万
• 依托单位: Carnegie-Mellon University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804548&HistoricalAwards=false
• 关键词: Synergizing; Surfactants; Electric; Fields; Engineer

Many materials are made up of blends of fluids, such as oil and water, that do not mix. The processing and control of these materials affects industries from food and pharmaceutical processing to oil recovery that are vital to our economy. This research will provide tools to guide the use of electric fields to manipulate these fluid systems including emulsions, blends, droplets, foams, and many soft materials. The use of electric fields has the potential to be more energy efficient and to allow for more intricate control of the properties of these materials than mechanical stirring. A critical step is understanding how electric fields interact with certain additives called surfactants. Surfactants are compounds that adsorb at the interface between two fluids and are ubiquitous in industrially relevant systems. The researchers will combine experimental studies, computational work, and molecular design of additives to improve existing processes and potentially develop new approaches to material processing.Electric fields are integral to a variety of processes that control multiphase complex fluid systems. Electrocoalescence, jetting, printing, dielectrophoretic manipulation on microfluidic chips, capillary electrophoresis and other processes use electric fields to break, deform, and coalesce fluid interfaces. Electric fields have the advantage of high spatial and temporal control and a quadratic, rather than linear, dependence of power on field strength. These advantages have been exploited in a limited number of processes involving fluid-fluid interfaces; however, broader development has been limited. A lack of understanding of the coupling between applied electric fields and surface active species is at the core of this, hindering the optimization of existing processes and the development of novel low-power electric-field driven replacements of existing mechanical processes. The principal investigators have established synergistic computational and experimental platforms to quantify the influence of electric fields on the electro-hydrodynamic deformation of fluid interfaces, drops, and bubbles. In particular, they have shown that additional time scales associated with electrical transport (e.g. due to charge relaxation) lead to deformation dynamics that are significantly richer than the more familiar scenario of a drop deformed by an imposed fluid flow. In many instances, surface active molecules, or surfactants, accumulate at fluid-fluid interfaces, and their transport dynamics brings further timescales that impact interfacial mechanics. However, fundamental understanding of the interplay of surfactant dynamics and imposed electric fields on the dynamics of fluid interfaces is lacking. Such an understanding is needed to avoid undesirable behavior such as drop breakup in coalescence devices, whose operation at present is guided by empirical observations. The hypothesis that drives this work is that the combined effects of electrohydrodynamics and surfactant transport can be tuned to enable control of drop deformation and break up, which will result in unique techniques to manipulate fluid interfaces in multiphase processes. This hypothesis will be tested using a synergistic experimental and computational approach.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

许多材料由不混合的流体混合物（例如油和水）组成。 这些材料的加工和控制影响着从食品和制药加工到石油回收的行业，这些行业对我们的经济至关重要。 这项研究将提供工具来指导使用电场来操纵这些流体系统，包括乳液，混合物，液滴，泡沫和许多软材料。 与机械搅拌相比，电场的使用具有更节能的潜力，并且允许对这些材料的性质进行更复杂的控制。 关键的一步是了解电场如何与称为表面活性剂的某些添加剂相互作用。 表面活性剂是吸附在两种流体之间的界面处的化合物，并且在工业相关系统中普遍存在。 研究人员将把联合收割机的实验研究、计算工作和添加剂的分子设计结合起来，以改进现有工艺，并有可能开发新的材料加工方法。电场是控制多相复杂流体系统的各种过程不可或缺的一部分。微流控芯片上的电聚结、喷射、印刷、介电泳操作、毛细管电泳和其他过程使用电场来破坏、变形和聚结流体界面。 电场具有高度的空间和时间控制以及功率对场强的二次依赖性而不是线性依赖性的优点。 这些优点已经在涉及流体-流体界面的有限数量的过程中被利用;然而，更广泛的发展受到限制。 缺乏对所施加的电场和表面活性物质之间的耦合的理解是这一点的核心，阻碍了现有工艺的优化和现有机械工艺的新型低功率电场驱动替代品的开发。主要研究人员已经建立了协同计算和实验平台，以量化电场对流体界面，液滴和气泡的电流体动力学变形的影响。特别地，他们已经表明，与电传输（例如，由于电荷弛豫）相关联的附加时间尺度导致比由施加的流体流变形的液滴的更熟悉的场景显著更丰富的变形动力学。在许多情况下，表面活性分子或表面活性剂在流体-流体界面处积聚，并且它们的传输动力学带来影响界面力学的进一步时间尺度。然而，缺乏对表面活性剂动力学和施加电场对流体界面动力学的相互作用的基本理解。这种理解是必要的，以避免不希望的行为，如在聚结装置，其操作目前是由经验观察指导液滴破裂。驱动这项工作的假设是，电流体动力学和表面活性剂传输的组合效应可以调整，以控制液滴变形和破裂，这将导致在多相过程中操纵流体界面的独特技术。 该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Numerical and asymptotic analysis of the three-dimensional electrohydrodynamic interactions of drop pairs

• DOI: 10.1017/jfm.2020.1007
• 发表时间: 2020-04
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Chiara Sorgentone;Jeremy I. Kach;Aditya S. Khair;L. Walker;Petia M. Vlahovska

Dynamic interfacial tension measurement under electric fields allows detection of charge carriers in nonpolar liquids

电场下的动态界面张力测量可以检测非极性液体中的电荷载流子

• DOI: 10.1016/j.jcis.2020.01.081
• 发表时间: 2020
• 期刊: Journal of Colloid and Interface Science
• 影响因子: 9.9
• 作者: Sengupta, Rajarshi;Khair, Aditya S.;Walker, Lynn M.
• 通讯作者: Walker, Lynn M.

Prediction and measurement of leaky dielectric drop interactions

漏电介质滴相互作用的预测和测量

• DOI: 10.1103/physrevfluids.7.013701
• 发表时间: 2022
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Kach, Jeremy I.;Walker, Lynn M.;Khair, Aditya S.
• 通讯作者: Khair, Aditya S.

Deformation of a conducting drop in a randomly fluctuating electric field

随机波动电场中导电液滴的变形

• DOI: 10.1103/physrevfluids.5.063701
• 发表时间: 2020
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Sengupta, Rajarshi;Walker, Lynn M.;Khair, Aditya S.
• 通讯作者: Khair, Aditya S.

Electric fields enable tunable surfactant transport to microscale fluid interfaces

电场使可调节的表面活性剂传输到微尺度流体界面

• DOI: 10.1103/physreve.100.023114
• 发表时间: 2019
• 期刊: Physical Review E
• 影响因子: 2.4
• 作者: Sengupta, Rajarshi;Khair, Aditya S.;Walker, Lynn M.
• 通讯作者: Walker, Lynn M.