Liquid Crystal Films Across Scales: Dewetting and Dielectrowetting

跨尺度的液晶薄膜：反润湿和介电润湿

• 批准号: 1815613
• 负责人: Linda Cummings
• 金额: $ 34.58万
• 依托单位: New Jersey Institute of Technology
• 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: 2018-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1815613&HistoricalAwards=false
• 关键词: Liquid; Crystal; Films; Across; Scales

The investigators will study problems of direct relevance to industrial applications of Nematic Liquid Crystals (NLCs), as well as of fundamental mathematical and scientific interest. The project will first focus on developing new approaches to model and accurately simulate the complex dewetting phenomena that have been observed in ultra-thin films of NLCs. The investigators will then model the phenomenon of dielectrowetting, driven by carefully-tuned applied electric fields. The spreading and dewetting problems to be considered are directly applicable to various industrial processes that rely on coating thin films of NLC onto substrates, such as the manufacture of NLC-based microdisplays for electronic devices, for which the development of robust predictive models would be very valuable. The work will also inform the use of dielectric fluids as optical shutters and as controllable lenses, and of NLCs in various biosensing applications. Establishing a firm theoretical framework for the experimentally-observed dewetting phenomena, and establishing models for controllable dielectrowetting, will be of significant interest both to researchers in industry and to a large class of academic researchers from the mathematics, physics and engineering communities. Both investigators are actively involved in teaching and mentoring undergraduate and graduate students at NJIT, within both mathematics and the engineering and physical sciences. A significant portion of the research for this project will be carried out by graduate students, who will receive an excellent introduction to research and a thorough training in research practices. The investigators will continue their involvement with undergraduate education under the present project, with the development of a new dielectrowetting experimental module for NJIT's Capstone Course in Applied Mathematics, providing the involved students with a unique educational and research experience that will ready them to join the U.S. scientific workforce.The project will develop new approaches to model and accurately simulate the complex dewetting phenomena observed in ultra-thin films of NLCs and model the phenomenon of dielectrowetting, driven by electric field gradients. The proposed work will combine careful mathematical modeling with a broad range of analytical approaches, such as matched asymptotic analysis, multiple scales analysis, local analysis of singularities, stability analysis of PDEs, marginal stability analysis, and regularization techniques. In parallel, numerical methods will be refined and developed for 4th order nonlinear parabolic PDEs arising from the free surface film-spreading models (ADI methods), and for the coupled elliptic models that will arise from the electric field. The codes will be implemented in a GPU computing environment for maximum efficiency and speed. Significant challenges include the derivation of physically-appropriate yet mathematically tractable models, necessary to gain insight into the problems considered; understanding the mechanisms leading to NLC film breakup; and dealing properly with the coupling between an applied nonuniform field and a moving NLC film, particularly in the case where the electric field is significant throughout the NLC layer. Wherever possible, the results will be compared either with existing, or new experiments that will be carried out in coordination with the theoretical and computational work on which this project centers. In addition to the potential industrial impacts, the project will provide both graduate and undergraduate students with significant educational and research training opportunities.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.

研究人员将研究与向列相液晶（NLC）的工业应用直接相关的问题，以及基本的数学和科学兴趣。该项目将首先专注于开发新的方法来建模和准确模拟在NLC超薄薄膜中观察到的复杂去湿现象。然后，研究人员将对介电润湿现象进行建模，该现象由仔细调整的外加电场驱动。要考虑的铺展和去湿问题直接适用于依赖于将NLC薄膜涂覆到基板上的各种工业过程，例如用于电子设备的基于NLC的微显示器的制造，对于这些工业过程，稳健的预测模型的开发将是非常有价值的。这项工作还将通知使用介电流体作为光学快门和可控透镜，以及在各种生物传感应用中的NLC。建立一个坚实的理论框架的实验观察到的去湿现象，并建立可控的介电润湿模型，将显着的兴趣，无论是在工业界的研究人员和一个大类的学术研究人员从数学，物理和工程界。两位研究人员都积极参与教学和指导NJIT的本科生和研究生，包括数学、工程和物理科学。该项目的研究的一个重要部分将由研究生进行，他们将获得一个很好的介绍研究和研究实践的全面培训。研究人员将继续参与本项目下的本科教育，为NJIT的应用数学顶点课程开发一个新的介电润湿实验模块，为参与的学生提供独特的教育和研究经验，使他们能够加入美国的科学队伍。该项目将开发新的方法来建模和精确模拟复杂的去湿现象观察到在超薄薄膜的NLC和模型的介电润湿现象，由电场梯度驱动。拟议的工作将结合联合收割机仔细的数学建模与广泛的分析方法，如匹配渐近分析，多尺度分析，局部奇异性分析，稳定性分析的偏微分方程，边际稳定性分析，和正则化技术。同时，数值方法将被细化和开发的自由表面膜扩展模型（ADI方法）所产生的四阶非线性抛物型偏微分方程，并为耦合椭圆模型，将产生的电场。这些代码将在GPU计算环境中实现，以获得最高的效率和速度。重大的挑战包括推导物理上适当的数学上易于处理的模型，需要深入了解所考虑的问题;理解导致NLC膜破裂的机制;以及正确处理施加的非均匀场和移动的NLC膜之间的耦合，特别是在电场在整个NLC层中很重要的情况下。只要有可能，结果将与现有的或新的实验进行比较，这些实验将与本项目所关注的理论和计算工作协调进行。除了潜在的工业影响外，该项目还将为研究生和本科生提供重要的教育和研究培训机会。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Computing dynamics of thin films via large scale GPU-based simulations

通过基于 GPU 的大规模模拟计算薄膜动力学

• DOI: 10.1016/j.jcpx.2018.100001
• 发表时间: 2019
• 期刊: Journal of Computational Physics: X
• 作者: Lam, Michael-Angelo Y.-H.;Cummings, Linda J.;Kondic, Lou
• 通讯作者: Kondic, Lou

Laser heating and melting of metals on nanoscale: breakup of metal filaments

纳米级金属的激光加热和熔化：金属丝的断裂

• 发表时间: 2023
• 期刊: Proceedings of the 17th International Heat Transfer Conference
• 作者: Allaire, R.;Cummings, L.
• 通讯作者: Cummings, L.

Instabilities of nematic liquid crystal films

向列液晶薄膜的不稳定性

• DOI: 10.1016/j.cocis.2021.101478
• 发表时间: 2021
• 期刊: Current Opinion in Colloid & Interface Science
• 影响因子: 8.9
• 作者: Kondic, L.;Cummings, L.J.
• 通讯作者: Cummings, L.J.

The Role of Phase Separation on Rayleigh-Plateau Type Instabilities in Alloys

• DOI: 10.1021/acs.jpcc.0c08720
• 发表时间: 2021-03-09
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY C
• 影响因子: 3.7
• 作者: Allaire, Ryan H.;Kondic, Lou;Fuentes-Cabrera, Miguel
• 通讯作者: Fuentes-Cabrera, Miguel

Influence of thermal effects on the breakup of thin films of nanometric thickness

热效应对纳米厚度薄膜破裂的影响

• DOI: 10.1103/physrevfluids.7.064001
• 发表时间: 2022
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Allaire, R. H.;Cummings, L. J.;Kondic, L.
• 通讯作者: Kondic, L.